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Zhang J, Liu G, Wei J. Assembly and comparative analysis of the first complete mitochondrial genome of Setaria italica. PLANTA 2024; 260:23. [PMID: 38850310 DOI: 10.1007/s00425-024-04386-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 03/10/2024] [Indexed: 06/10/2024]
Abstract
MAIN CONCLUSION In this study, we assembled the first complete mitochondrial genome of Setaria italica and confirmed the multi-branched architecture. The foxtail millet (Setaria italica) holds significant agricultural importance, particularly in arid and semi-arid regions. It plays a pivotal role in diversifying dietary patterns and shaping planting strategies. Although the chloroplast genome of S. italica has been elucidated in recent studies, the complete mitochondrial genome remains largely unexplored. In this study, we employed PacBio HiFi sequencing platforms to sequence and assemble the complete mitochondrial genome. The mitochondrial genome spans a total length of 446,614 base pairs and harbors a comprehensive set of genetic elements, including 33 unique protein-coding genes (PCGs), encompassing 24 unique mitochondrial core genes and 9 variable genes, along with 20 transfer RNA (tRNA) genes and 3 ribosomal RNA (rRNA) genes. Our analysis of mitochondrial PCGs revealed a pronounced codon usage preference. For instance, the termination codon exhibits a marked preference for UAA, while alanine (Ala) exhibits a preference for GCU, and glutamine (Gln) favors CAA. Notably, the maximum Relative Synonymous Codon Usage (RSCU) values for cysteine (Cys) and phenylalanine (Phe) are both below 1.2, indicating a lack of strong codon usage preference for these amino acids. Phylogenetic analyses consistently place S. italica in close evolutionary proximity to Chrysopogon zizanioides, relative to other Panicoideae plants. Collinearity analysis showed that a total of 39 fragments were identified to display homology with both the mitochondrial and chloroplast genomes. A total of 417 potential RNA-editing sites were discovered across the 33 mitochondrial PCGs. Notably, all these editing events involved the conversion of cytosine (C) to uracil (U). Through the employment of PCR validation coupled with Sanger sequencing for the anticipated editing sites of these codons, RNA-editing events were conclusively identified at two specific loci: nad4L-2 and atp6-1030. The results of this study provide a pivotal foundation for advanced genomic breeding research in foxtail millet. Furthermore, they impart essential insights that will be instrumental for forthcoming investigations into the evolutionary and molecular dynamics of Panicoideae species.
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Affiliation(s)
- Jiewei Zhang
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China.
| | - Guiming Liu
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China.
| | - Jianhua Wei
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China.
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2
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Yu X, Ma Z, Liu S, Duan Z. Analysis of the Rhodomyrtus tomentosa mitochondrial genome: Insights into repeat-mediated recombination and intra-cellular DNA transfer. Gene 2024; 909:148288. [PMID: 38367854 DOI: 10.1016/j.gene.2024.148288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 02/06/2024] [Accepted: 02/12/2024] [Indexed: 02/19/2024]
Abstract
Plant mitochondrial genomes participate in encoding proteins crucial to the major producers of ATP in the cell and replication and heredity of their own DNA. The sequences and structure of the plant mitochondrial genomes profoundly impact these fundamental processes, and studies of plant mitochondrial genomes are needed. We reported the complete sequences of the Rhodomyrtus tomentosa mitochondrial genome here, totaling 400,482 bp. Nanopore ONT reads and PCR amplification provided evidence for recombination mediated by the eight repeat pairs for the R. tomentosa mitochondrial genome. Thirty-eight genes were identified in the R. tomentosa mitochondrial genome. Comparative analyses of the mitochondrial genome and plastome and PCR amplification suggest that five fragments of mitochondrial plastid DNA were unfunctional sequences resulting from intracellular gene transfer. Phylogenetic analysis based on each and all of the 27 mitochondrial protein-coding genes of nine Myrtales species revealed that R. tomentosa always clustered with other species of Myrtaceae. This study uncovered the enormous complexity of the R. tomentosa mitochondrial genome, the active repeat-mediated recombinations, the presence of mitochondrial plastid DNAs, and the topological incongruence of Myrtales among the single-gene trees.
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Affiliation(s)
- Xiaoli Yu
- School of Life Science, Huizhou University, Huizhou 516007, Guangdong, China.
| | - Zhengbing Ma
- Forestry Technology Extension Station of Huiyang, Huizhou 516211, Guangdong, China.
| | - Shu Liu
- School of Life Science, Huizhou University, Huizhou 516007, Guangdong, China.
| | - Zhonggang Duan
- School of Life Science, Huizhou University, Huizhou 516007, Guangdong, China.
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3
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Guo H, Liu Q, Chen Y, Niu H, Zhao Q, Song H, Pang R, Huang X, Zhang J, Zhao Z, Liu D, Zhu J. Comprehensive assembly and comparative examination of the full mitochondrial genome in Castanea mollissima Blume. Genomics 2023; 115:110740. [PMID: 37923179 DOI: 10.1016/j.ygeno.2023.110740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/23/2023] [Accepted: 10/31/2023] [Indexed: 11/07/2023]
Abstract
The Chinese chestnut, Castanea mollissima Blume, a nut-bearing tree native to China and North Korea, belongs to the Fagaceae family. As an important genetic resource, C. mollissima is vital in enhancing edible chestnut varieties and offers significant insights into the origin and evolution of chestnut species. While the chloroplast genome of C. mollissima has been sequenced, its mitochondrial genome (mitogenome) remains largely uncharted. In this study, we have characterized the C. mollissima mitogenome, assembling it utilizing reads from both BGI and Nanopore sequencing platforms, and conducted a comparative analysis with the mitochondrial genomes of closely related species. The mitogenome of C. mollissima manifests a polycyclic structure consisting of two circular molecules measuring 363,232 bp and 24,806 bp, respectively. This genome encompasses 35 unique protein-coding genes, 19 tRNA genes, and three rRNA genes. A total of 139 SSRs were identified throughout the entire C. mollissima mitogenome. Furthermore, the combined length of homologous fragments between the chloroplast and mitochondrial genomes was 5766 bp, constituting 1.49% of the mitogenome. We also predicted 484 RNA editing sites in C. mollissima, demonstrating C-to-U RNA editing. Phylogenetic analysis of related species' mitogenomes showed that C. mollissima was closely related to Lithocarpus litseifolius (Hance) Chun and Quercus acutissima Carruth. Interestingly, the mitogenome sequences of C. mollissima, L. litseifolius, Q. acutissima, Fagus sylvatica L., and Juglans mandshurica Maxim did not show conservation in their alignments, indicating frequent genome reorganization. This report marks the inaugural study of the C. mollissima mitogenome, serving as a benchmark genome for economically significant plants within the Castanea genus. Moreover, it supplies invaluable information that can guide future molecular breeding efforts and contribute to the broader understanding of chestnut genomics.
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Affiliation(s)
- Haili Guo
- Shandong Provincial Center of Forest and Grass Germplasm Resources, Jinan 250102, China
| | - Qiong Liu
- Shandong Refining and Chemical Energy Group Co., Ltd., Jinan 250199, China
| | - Ying Chen
- Shandong Provincial Forestry Protection and Development Service Center, Jinan 250109, China
| | - Hongyun Niu
- Shandong Provincial Center of Aviation Emergency and Rescue, Jinan 250014, China
| | | | - Hui Song
- Shandong Institute of Land Spatial Data and Remote Sensing Technology, Jinan 250002, China
| | - Ruidong Pang
- Shandong Provincial Archives of Natural Resources, Jinan 250013, China
| | - Xiaolu Huang
- Guangxi Forestry Research Institute, Nanning 530002, China
| | - Jingzheng Zhang
- Engineering Research Center of Chestnut Industry Technology, Ministry of Education, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China
| | - Zhiheng Zhao
- Guangxi Forestry Research Institute, Nanning 530002, China; Engineering Research Center of Chestnut Industry Technology, Ministry of Education, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China.
| | - Dan Liu
- Shandong Provincial Center of Forest and Grass Germplasm Resources, Jinan 250102, China.
| | - Jingle Zhu
- Research Institute of Non-Timber Forestry, Chinese Academy of Forestry, Zhengzhou 450003, China.
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Peralta-Castro A, Cordoba-Andrade F, Díaz-Quezada C, Sotelo-Mundo R, Winkler R, Brieba LG. The plant organellar primase-helicase directs template recognition and primosome assembly via its zinc finger domain. BMC PLANT BIOLOGY 2023; 23:467. [PMID: 37803262 PMCID: PMC10557236 DOI: 10.1186/s12870-023-04477-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 09/19/2023] [Indexed: 10/08/2023]
Abstract
BACKGROUND The mechanisms and regulation for DNA replication in plant organelles are largely unknown, as few proteins involved in replisome assembly have been biochemically studied. A primase-helicase dubbed Twinkle (T7 gp4-like protein with intramitochondrial nucleoid localization) unwinds double-stranded DNA in metazoan mitochondria and plant organelles. Twinkle in plants is a bifunctional enzyme with an active primase module. This contrast with animal Twinkle in which the primase module is inactive. The organellar primase-helicase of Arabidopsis thaliana (AtTwinkle) harbors a primase module (AtPrimase) that consists of an RNA polymerase domain (RPD) and a Zn + + finger domain (ZFD). RESULTS Herein, we investigate the mechanisms by which AtTwinkle recognizes its templating sequence and how primer synthesis and coupling to the organellar DNA polymerases occurs. Biochemical data show that the ZFD of the AtPrimase module is responsible for template recognition, and this recognition is achieved by residues N163, R166, and K168. The role of the ZFD in template recognition was also corroborated by swapping the RPDs of bacteriophage T7 primase and AtPrimase with their respective ZFDs. A chimeric primase harboring the ZFD of T7 primase and the RPD of AtPrimase synthesizes ribonucleotides from the T7 primase recognition sequence and conversely, a chimeric primase harboring the ZFD of AtPrimase and the RPD of T7 primase synthesizes ribonucleotides from the AtPrimase recognition sequence. A chimera harboring the RPDs of bacteriophage T7 and the ZBD of AtTwinkle efficiently synthesizes primers for the plant organellar DNA polymerase. CONCLUSIONS We conclude that the ZFD is responsible for recognizing a single-stranded sequence and for primer hand-off into the organellar DNA polymerases active site. The primase activity of plant Twinkle is consistent with phylogeny-based reconstructions that concluded that Twinkle´s last eukaryotic common ancestor (LECA) was an enzyme with primase and helicase activities. In plants, the primase domain is active, whereas the primase activity was lost in metazoans. Our data supports the notion that AtTwinkle synthesizes primers at the lagging-strand of the organellar replication fork.
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Affiliation(s)
- Antolin Peralta-Castro
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821, Irapuato Guanajuato, Mexico
| | - Francisco Cordoba-Andrade
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821, Irapuato Guanajuato, Mexico
| | - Corina Díaz-Quezada
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821, Irapuato Guanajuato, Mexico
| | - Rogerio Sotelo-Mundo
- Laboratorio de Estructura Biomolecular, Centro de Investigación en Alimentación y Desarrollo, A.C. Carretera Gustavo Enrique Astiazarán Rosas Núm. 46, Ejido a La Victoria, 83304, Hermosillo, Sonora, Mexico
| | - Robert Winkler
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821, Irapuato Guanajuato, Mexico
| | - Luis G Brieba
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821, Irapuato Guanajuato, Mexico.
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Yang H, Chen H, Ni Y, Li J, Cai Y, Wang J, Liu C. Mitochondrial Genome Sequence of Salvia officinalis (Lamiales: Lamiaceae) Suggests Diverse Genome Structures in Cogeneric Species and Finds the Stop Gain of Genes through RNA Editing Events. Int J Mol Sci 2023; 24:ijms24065372. [PMID: 36982448 PMCID: PMC10048906 DOI: 10.3390/ijms24065372] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/20/2023] [Accepted: 03/02/2023] [Indexed: 03/14/2023] Open
Abstract
Our previous study was the first to confirm that the predominant conformation of mitochondrial genome (mitogenome) sequence of Salvia species contains two circular chromosomes. To further understand the organization, variation, and evolution of Salvia mitogenomes, we characterized the mitogenome of Salvia officinalis. The mitogenome of S. officinalis was sequenced using Illumina short reads and Nanopore long reads and assembled using a hybrid assembly strategy. We found that the predominant conformation of the S. officinalis mitogenome also had two circular chromosomes that were 268,341 bp (MC1) and 39,827 bp (MC2) in length. The S. officinalis mitogenome encoded an angiosperm-typical set of 24 core genes, 9 variable genes, 3 rRNA genes, and 16 tRNA genes. We found many rearrangements of the Salvia mitogenome through inter- and intra-specific comparisons. A phylogenetic analysis of the coding sequences (CDs) of 26 common protein-coding genes (PCGs) of 11 Lamiales species and 2 outgroup taxa strongly indicated that the S. officinalis was a sister taxon to S. miltiorrhiza, consistent with the results obtained using concatenated CDs of common plastid genes. The mapping of RNA-seq data to the CDs of PCGs led to the identification of 451 C-to-U RNA editing sites from 31 PCGs of the S. officinalis mitogenome. Using PCR amplification and Sanger sequencing methods, we successfully validated 113 of the 126 RNA editing sites from 11 PCGs. The results of this study suggest that the predominant conformation of the S. officinalis mitogenome are two circular chromosomes, and the stop gain of rpl5 was found through RNA editing events of the Salvia mitogenome.
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Affiliation(s)
- Heyu Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Haimei Chen
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Yang Ni
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Jingling Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Yisha Cai
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Jiehua Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
- Correspondence: (J.W.); (C.L.); Tel.: +86-022-8740-2072 (J.W.); +86-10-5783-3111 (C.L.); Fax: +86-022-2740-7956 (J.W.); +86-10-62899715 (C.L.)
| | - Chang Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
- Correspondence: (J.W.); (C.L.); Tel.: +86-022-8740-2072 (J.W.); +86-10-5783-3111 (C.L.); Fax: +86-022-2740-7956 (J.W.); +86-10-62899715 (C.L.)
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6
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Liu J, Ni Y, Liu C. Polymeric structure of the Cannabis sativa L. mitochondrial genome identified with an assembly graph model. Gene 2023; 853:147081. [PMID: 36470482 DOI: 10.1016/j.gene.2022.147081] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/14/2022] [Accepted: 11/28/2022] [Indexed: 12/03/2022]
Abstract
Cannabis sativa L. belongs to the family Cannabaceae in Rosales. It has been widely used as medicines, building materials, and textiles. Elucidating its genome is critical for molecular breeding and synthetic biology study. Many studies have shown that the mitochondrial genomes (mitogenomes) and even chloroplast genomes (plastomes) had complex polymeric structures. Using the Nanopore sequencing platform, we sequenced, assembled, and analyzed its mitogenome and plastome. The resulting unitig graph suggested that the mitogenome had a complex polymeric structure. However, a gap-free, circular sequence was further assembled from the unitig graph. In contrast, a circular sequence representing the plastome was obtained. The mitogenome major conformation was 415,837 bp long, and the plastome was 153,927 bp long. To test if the repeat sequences promote recombination, which corresponds to the branch points in the structure, we tested the sequences around repeats by long-read mapping. Among 208 pairs of predicted repeats, the mapping results supported the presence of cross-over around 25 pairs of repeats. Subsequent PCR amplification confirmed the presence of cross-over around 15 of the 25 repeats. By comparing the mitogenome and plastome sequences, we identified 19 mitochondria plastid DNAs, including seven complete genes (trnW-CCA, trnP-UGG, psbJ, trnN-GUU, trnD-GUC, trnH-GUG, trnM-CAU) and nine gene fragments. Furthermore, the selective pressure analysis results showed that five genes (atp1, ccmB, ccmC, cox1, nad7) had 19 positively selected sites. Lastly, we predicted 28 RNA editing sites. A total of 8 RNA editing sites located in the coding regions were successfully validated by PCR amplification and Sanger sequencing, of which four were synonymous, and four were nonsynonymous. In particular, the RNA editing events appeared to be tissue-specific in C. sativa mitogenome. In summary, we have confirmed the major confirmation of C. sativa mitogenome and characterized its structural features in detail. These results provide critical information for future variety breeding and resource development for C. sativa.
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Affiliation(s)
- Jingting Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, PR China
| | - Yang Ni
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, PR China
| | - Chang Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, PR China.
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He W, Xiang K, Chen C, Wang J, Wu Z. Master graph: an essential integrated assembly model for the plant mitogenome based on a graph-based framework. Brief Bioinform 2023; 24:bbac522. [PMID: 36644898 DOI: 10.1093/bib/bbac522] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/03/2022] [Accepted: 11/02/2022] [Indexed: 01/17/2023] Open
Abstract
Unlike the typical single circular structure of most animal mitochondrial genomes (mitogenome), the drastic structural variation of plant mitogenomes is a result of a mixture of molecules of various sizes and structures. Obtaining the full panoramic plant mitogenome is still considered a roadblock in evolutionary biology. In this study, we developed a graph-based sequence assembly toolkit (GSAT) to construct the pan-structural landscape of plant mitogenome with high-quality mitochondrial master graphs (MMGs) for model species including rice (Oryza sativa) and thale cress (Arabidopsis thaliana). The rice and thale cress MMGs have total lengths of 346 562 and 358 041 bp, including 9 and 6 contigs and 12 and 8 links, respectively, and could be further divided into 6 and 3 minimum master circles and 4 and 2 minimum secondary circles separately. The nuclear mitochondrial DNA segments (NUMTs) in thale cress strongly affected the frequency evaluation of the homologous structures in the mitogenome, while the effects of NUMTs in rice were relatively weak. The mitochondrial plastid DNA segments (MTPTs) in both species had no effects on the assessment of the MMGs. All potential recombinant structures were evaluated, and the findings revealed that all, except for nuclear-homologous structures, MMG structures are present at a much higher frequency than non-MMG structures are. Investigations of potential circular and linear molecules further supported multiple dominant structures in the mitogenomes and could be completely summarized in the MMG. Our study provided an efficient and accurate model for assembling and applying graph-based plant mitogenomes to assess their pan-structural variations.
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Affiliation(s)
- Wenchuang He
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Kunli Xiang
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Caijin Chen
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Jie Wang
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Zhiqiang Wu
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
- Kunpeng Institute of Modern Agriculture at Foshan, Chinese Academy of Agricultural Sciences, Foshan 528200, China
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Liu D, Qu K, Yuan Y, Zhao Z, Chen Y, Han B, Li W, El-Kassaby YA, Yin Y, Xie X, Tong B, Liu H. Complete sequence and comparative analysis of the mitochondrial genome of the rare and endangered Clematis acerifolia, the first clematis mitogenome to provide new insights into the phylogenetic evolutionary status of the genus. Front Genet 2023; 13:1050040. [PMID: 36761694 PMCID: PMC9907779 DOI: 10.3389/fgene.2022.1050040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/05/2022] [Indexed: 01/05/2023] Open
Abstract
Clematis is one of the large worldwide genera of the Ranunculaceae Juss. Family, with high ornamental and medicinal value. China is the modern distribution centre of Clematis with abundant natural populations. Due to the complexity and high morphological diversity of Clematis, the genus is difficult to classify systematically, and in particular, the phylogenetic position of the endangered Clematis acerifolia is highly controversial. The use of the mitochondrial complete genome is a powerful molecular method that is frequently used for inferring plants phylogenies. However, studies on Clematis mitogenome are rare, thus limiting our full understanding of its phylogeny and genome evolution. Here, we sequenced and annotated the C. acerifolia mt genome using Illumina short- and Nanopore long-reads, characterized the species first complete mitogenome, and performed a comparative phylogenetic analysis with its close relatives. The total length of the C. acerifolia mitogenome is 698,247 bp and the main structure is multi-branched (linear molecule 1 and circular molecule 2). We annotated 55 genes, including 35 protein-coding, 17 tRNA, and 3 rRNA genes. The C. acerifolia mitogenome has extremely unconserved structurally, with extensive sequence transfer between the chloroplast and mitochondrial organelles, sequence repeats, and RNA editing. The phylogenetic position of C. acerifolia was determined by constructing the species mitogenome with 24 angiosperms. Further, our C. acerifolia mitogenome characteristics investigation included GC contents, codon usage, repeats and synteny analysis. Overall, our results are expected to provide fundamental information for C. acerifolia mitogenome evolution and confirm the validity of mitochondrial analysis in determining the phylogenetic positioning of Clematis plants.
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Affiliation(s)
- Dan Liu
- Shandong Provincial Center of Forest and Grass Germplasm Resources, Jinan, China,State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Kai Qu
- State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Yangchen Yuan
- College of Landscape Architecture and Tourism, Hebei Agricultural University, Baoding, China,Hebei Hongya Mountain State-Owned Forest Farm, Baoding, China
| | - Zhiheng Zhao
- Guangxi Forestry Research Institute, Guangxi Key Laboratory of Special Non-wood Forest Cultivation &; Utilization, Nanning, China
| | - Ying Chen
- Forestry Protection and Development Service Center of Shandong Province, Jinan, China
| | - Biao Han
- Shandong Provincial Center of Forest and Grass Germplasm Resources, Jinan, China
| | - Wei Li
- State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Yousry A. El-Kassaby
- Department of Forest and Conservation Sciences, The University of British Columbia, Vancouver, BC, Canada
| | | | - Xiaoman Xie
- Shandong Provincial Center of Forest and Grass Germplasm Resources, Jinan, China,*Correspondence: Xiaoman Xie, ; Boqiang Tong, ; Hongshan Liu,
| | - Boqiang Tong
- Shandong Provincial Center of Forest and Grass Germplasm Resources, Jinan, China,*Correspondence: Xiaoman Xie, ; Boqiang Tong, ; Hongshan Liu,
| | - Hongshan Liu
- Hebei Hongya Mountain State-Owned Forest Farm, Baoding, China,*Correspondence: Xiaoman Xie, ; Boqiang Tong, ; Hongshan Liu,
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9
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Super-Mitobarcoding in Plant Species Identification? It Can Work! The Case of Leafy Liverworts Belonging to the Genus Calypogeia. Int J Mol Sci 2022; 23:ijms232415570. [PMID: 36555212 PMCID: PMC9779425 DOI: 10.3390/ijms232415570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/04/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
Molecular identification of species is especially important where traditional taxonomic methods fail. The genus Calypogeia belongs to one of the tricky taxons. The simple morphology of these species and a tendency towards environmental plasticity make them complicated in identification. The finding of the universal single-locus DNA barcode in plants seems to be 'the Holy Grail'; therefore, researchers are increasingly looking for multiloci DNA barcodes or super-barcoding. Since the mitochondrial genome has low sequence variation in plants, species delimitation is usually based on the chloroplast genome. Unexpectedly, our research shows that super-mitobarcoding can also work! However, our outcomes showed that a single method of molecular species delimitation should be avoided. Moreover, it is recommended to interpret the results of molecular species delimitation alongside other types of evidence, such as ecology, population genetics or comparative morphology. Here, we also presented genetic data supporting the view that C. suecica is not a homogeneous species.
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10
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Kersten B, Rellstab C, Schroeder H, Brodbeck S, Fladung M, Krutovsky KV, Gugerli F. The mitochondrial genome sequence of Abies alba Mill. reveals a high structural and combinatorial variation. BMC Genomics 2022; 23:776. [PMID: 36443651 PMCID: PMC9703787 DOI: 10.1186/s12864-022-08993-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 11/05/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Plant mitogenomes vary widely in size and genomic architecture. Although hundreds of plant mitogenomes of angiosperm species have already been sequence-characterized, only a few mitogenomes are available from gymnosperms. Silver fir (Abies alba) is an economically important gymnosperm species that is widely distributed in Europe and occupies a large range of environmental conditions. Reference sequences of the nuclear and chloroplast genome of A. alba are available, however, the mitogenome has not yet been assembled and studied. RESULTS Here, we used paired-end Illumina short reads generated from a single haploid megagametophyte in combination with PacBio long reads from high molecular weight DNA of needles to assemble the first mitogenome sequence of A. alba. Assembly and scaffolding resulted in 11 mitogenome scaffolds, with the largest scaffold being 0.25 Mbp long. Two of the scaffolds displayed a potential circular structure supported by PCR. The total size of the A. alba mitogenome was estimated at 1.43 Mbp, similar to the size (1.33 Mbp) of a draft assembly of the Abies firma mitogenome. In total, 53 distinct genes of known function were annotated in the A. alba mitogenome, comprising 41 protein-coding genes, nine tRNA, and three rRNA genes. The proportion of highly repetitive elements (REs) was 0.168. The mitogenome seems to have a complex and dynamic structure featured by high combinatorial variation, which was specifically confirmed by PCR for the contig with the highest mapping coverage. Comparative analysis of all sequenced mitogenomes of gymnosperms revealed a moderate, but significant positive correlation between mitogenome size and proportion of REs. CONCLUSIONS The A. alba mitogenome provides a basis for new comparative studies and will allow to answer important structural, phylogenetic and other evolutionary questions. Future long-read sequencing with higher coverage of the A. alba mitogenome will be the key to further resolve its physical structure. The observed positive correlation between mitogenome size and proportion of REs will be further validated once available mitogenomes of gymnosperms would become more numerous. To test whether a higher proportion of REs in a mitogenome leads to an increased recombination and higher structural complexity and variability is a prospective avenue for future research.
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Affiliation(s)
- Birgit Kersten
- Thünen Institute of Forest Genetics, Sieker Landstrasse 2, 22927 Grosshansdorf, Germany
| | - Christian Rellstab
- grid.419754.a0000 0001 2259 5533Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Hilke Schroeder
- Thünen Institute of Forest Genetics, Sieker Landstrasse 2, 22927 Grosshansdorf, Germany
| | - Sabine Brodbeck
- grid.419754.a0000 0001 2259 5533Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Matthias Fladung
- Thünen Institute of Forest Genetics, Sieker Landstrasse 2, 22927 Grosshansdorf, Germany
| | - Konstantin V. Krutovsky
- grid.7450.60000 0001 2364 4210Department of Forest Genetics and Forest Tree Breeding, Georg-August University of Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Felix Gugerli
- grid.419754.a0000 0001 2259 5533Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
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11
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Zhang K, Wang Y, Zhang X, Han Z, Shan X. Deciphering the mitochondrial genome of Hemerocallis citrina (Asphodelaceae) using a combined assembly and comparative genomic strategy. FRONTIERS IN PLANT SCIENCE 2022; 13:1051221. [PMID: 36466251 PMCID: PMC9715983 DOI: 10.3389/fpls.2022.1051221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 11/04/2022] [Indexed: 06/12/2023]
Abstract
Hemerocallis citrina is a perennial herbaceous plant that is dedicated to mothers in Chinese culture and is widely distributed across the country. As a popular species with a long history of cultivation and utilization, it is renowned for its remarkable edible and medicinal value. In this study, we integrated Illumina short-read and Oxford Nanopore long-read sequencing to generate a complete mitochondrial genome (mitogenome) assembly of H. citrina. The H. citrina mitogenome has a multiple chromosomal structure consisting of three circular molecules that are 45,607 bp, 239,991 bp, and 182,864 bp long. We correspondingly annotated 66 genes, comprising 45 protein-coding genes (PCGs), 17 tRNA genes, and 4 rRNA genes. Comparative analysis of gene organization indicated that six syntenic gene clusters were conserved in the mitogenomes of the compared plants. The investigation of repeat content revealed repeat-rich nature of the H. citrina mitogenome, for which plentiful dispersed repeats were characterized to correlate with the size of the mitogenome. The codon usage behavior disclosed that Leucine (Leu) and Serine (Ser) were the most preferred amino acids in H. citrina, and nearly all of the codons with relative synonymous codon usage (RSCU) values greater than 1 showed the preference of A or T ending. Moreover, we inferred a total of 679 RNA editing sites in all mitochondrial PCGs, which presented perfect C-to-U types and tended to lead to the alteration of internal codons. Subsequent selective pressure analysis showed that the majority of the PCGs had undergone evolutionary negative selections, with atp9 in particular undergoing strong stabilizing selection, reflecting its indispensable function in mitogenomes. According to the phylogenetic analysis, H. citrina is close to the species Allium cepa (Amaryllidaceae) and Asparagus officinalis (Asparagaceae) in evolutionary terms. Overall, this project presents the first complete mitogenome of H. citrina, which could provide a reference genome for the comprehensive exploration of the Asphodelaceae family and can facilitate further genomic breeding and evolutionary research on this medicine-food homologous plant.
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Affiliation(s)
- Kun Zhang
- College of Agriculture and Life Sciences, Shanxi Datong University, Datong, Shanxi, China
| | - Yiheng Wang
- Institute of Germplasm Resources and Biotechnology, Tianjin Academy of Agricultural Sciences, Tianjin, China
| | - Xun Zhang
- College of Agriculture and Life Sciences, Shanxi Datong University, Datong, Shanxi, China
| | - Zhiping Han
- College of Agriculture and Life Sciences, Shanxi Datong University, Datong, Shanxi, China
| | - Xiaofei Shan
- College of Agriculture and Life Sciences, Shanxi Datong University, Datong, Shanxi, China
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12
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Qian J, Zheng M, Wang L, Song Y, Yan J, Hsu YF. Arabidopsis mitochondrial single-stranded DNA-binding proteins SSB1 and SSB2 are essential regulators of mtDNA replication and homologous recombination. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2022; 64:1952-1965. [PMID: 35925893 DOI: 10.1111/jipb.13338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
Faithful DNA replication is one of the most essential processes in almost all living organisms. However, the proteins responsible for organellar DNA replication are still largely unknown in plants. Here, we show that the two mitochondrion-targeted single-stranded DNA-binding (SSB) proteins SSB1 and SSB2 directly interact with each other and act as key factors for mitochondrial DNA (mtDNA) maintenance, as their single or double loss-of-function mutants exhibit severe germination delay and growth retardation. The mtDNA levels in mutants lacking SSB1 and/or SSB2 function were two- to four-fold higher than in the wild-type (WT), revealing a negative role for SSB1/2 in regulating mtDNA replication. Genetic analysis indicated that SSB1 functions upstream of mitochondrial DNA POLYMERASE IA (POLIA) or POLIB in mtDNA replication, as mutation in either gene restored the high mtDNA copy number of the ssb1-1 mutant back to WT levels. In addition, SSB1 and SSB2 also participate in mitochondrial genome maintenance by influencing mtDNA homologous recombination (HR). Additional genetic analysis suggested that SSB1 functions upstream of ORGANELLAR SINGLE-STRANDED DNA-BINDING PROTEIN1 (OSB1) during mtDNA replication, while SSB1 may act downstream of OSB1 and MUTS HOMOLOG1 for mtDNA HR. Overall, our results yield new insights into the roles of the plant mitochondrion-targeted SSB proteins and OSB1 in maintaining mtDNA stability via affecting DNA replication and DNA HR.
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Affiliation(s)
- Jie Qian
- School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Min Zheng
- School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Lingyu Wang
- School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Yu Song
- School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Jiawen Yan
- School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Yi-Feng Hsu
- School of Life Sciences, Southwest University, Chongqing, 400715, China
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13
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Shen J, Li X, Li M, Cheng H, Huang X, Jin S. Characterization, comparative phylogenetic, and gene transfer analyses of organelle genomes of Rhododendron × pulchrum. FRONTIERS IN PLANT SCIENCE 2022; 13:969765. [PMID: 36212362 PMCID: PMC9532937 DOI: 10.3389/fpls.2022.969765] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Rhododendron × pulchrum, an important horticultural species, is widely distributed in Europe, Asia, and North America. To analyze the phylogenetic and organelle genome information of R. × pulchrum and its related species, the organelle genome of R. × pulchrum was sequenced and assembled. The complete mitochondrial genome showed lineage DNA molecules, which were 816,410 bp long and contained 64 genes, namely 24 transfer RNA (tRNA) genes, 3 ribosomal RNA (rRNA) genes, and 37 protein-coding genes. The chloroplast genome of R. × pulchrum was reassembled and re-annotated; the results were different from those of previous studies. There were 42 and 46 simple sequence repeats (SSR) identified from the mitochondrial and chloroplast genomes of R. × pulchrum, respectively. Five genes (nad1, nad2, nad4, nad7, and rps3) were potentially useful molecular markers. The R. × pulchrum mitochondrial genome collinear alignment among five species of the Ericaceae showed that the mitochondrial genomes of these related species have a high degree of homology with R. × pulchrum in this gene region, and the most conservative genes were trnC-GCA, trnD-GUC, trnM-CAU, trnN-GUU, trnY-GUA, atp4, nad4, nad2, nad5, ccmC, and rrn26. The phylogenetic trees of mitochondrial genome showed that R. simsii was a sister to R. × pulchrum. The results verified that there was gene rearrangement between R. × pulchrum and R. simsii mitochondrial genomes. The codon usage bias of 10 Ericaceae mitochondrial genes and 7 Rhododendron chloroplast genes were influenced by mutation, while other genes codon usages had undergone selection. The study identified 13 homologous fragments containing gene sequences between the chloroplast and mitochondrial genomes of R. × pulchrum. Overall, our results illustrate the organelle genome information could explain the phylogenetics of plants and could be used to develop molecular markers and genetic evolution. Our study will facilitate the study of population genetics and evolution in Rhododendron and other genera in Ericaceae.
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Affiliation(s)
| | - Xueqin Li
- Jiyang College, Zhejiang A&F University, Zhuji, China
- Department of Life Science and Health, Huzhou College, Huzhou, Zhejiang, China
| | - Mingzhi Li
- Bio and Data Biotechnology Co., Ltd., Guangzhou, China
| | - Hefeng Cheng
- Jiyang College, Zhejiang A&F University, Zhuji, China
| | | | - Songheng Jin
- Jiyang College, Zhejiang A&F University, Zhuji, China
- Department of Life Science and Health, Huzhou College, Huzhou, Zhejiang, China
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14
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Xiang QP, Tang JY, Yu JG, Smith DR, Zhu YM, Wang YR, Kang JS, Yang J, Zhang XC. The evolution of extremely diverged plastomes in Selaginellaceae (lycophyte) is driven by repeat patterns and the underlying DNA maintenance machinery. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:768-784. [PMID: 35648423 DOI: 10.1111/tpj.15851] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/25/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Two factors are proposed to account for the unusual features of organellar genomes: the disruptions of organelle-targeted DNA replication, repair, and recombination (DNA-RRR) systems in the nuclear genome and repetitive elements in organellar genomes. Little is known about how these factors affect organellar genome evolution. The deep-branching vascular plant family Selaginellaceae is known to have a deficient DNA-RRR system and convergently evolved organellar genomes. However, we found that the plastid genome (plastome) of Selaginella sinensis has extremely accelerated substitution rates, a low GC content, pervasive repeat elements, a dynamic network structure, and it lacks direct or inverted repeats. Unexpectedly, its organelle DNA-RRR system is short of a plastid-targeted Recombinase A1 (RecA1) and a mitochondrion-targeted RecA3, in line with other explored Selaginella species. The plastome contains a large collection of short- and medium-sized repeats. Given the absence of RecA1 surveillance, we propose that these repeats trigger illegitimate recombination, accelerated mutation rates, and structural instability. The correlations between repeat quantity and architectural complexity in the Selaginella plastomes support these conclusions. We, therefore, hypothesize that the interplay of the deficient DNA-RRR system and the high repeat content has led to the extraordinary divergence of the S. sinensis plastome. Our study not only sheds new light on the mechanism of plastome divergence by emphasizing the power of cytonuclear integration, but it also reconciles the longstanding contradiction on the effects of DNA-RRR system disruption on genome structure evolution.
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Affiliation(s)
- Qiao-Ping Xiang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
| | - Jun-Yong Tang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ji-Gao Yu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - David Roy Smith
- Department of Biology, University of Western Ontario, London, N6A 5B7, Ontario, Canada
| | - Yan-Mei Zhu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
| | - Ya-Rong Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
| | - Jong-Soo Kang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
| | - Jie Yang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xian-Chun Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
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15
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Fischer A, Dotzek J, Walther D, Greiner S. Graph-based models of the Oenothera mitochondrial genome capture the enormous complexity of higher plant mitochondrial DNA organization. NAR Genom Bioinform 2022; 4:lqac027. [PMID: 35372837 PMCID: PMC8969700 DOI: 10.1093/nargab/lqac027] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 03/02/2022] [Accepted: 03/09/2022] [Indexed: 12/26/2022] Open
Abstract
Plant mitochondrial genomes display an enormous structural complexity, as recombining repeat-pairs lead to the generation of various sub-genomic molecules, rendering these genomes extremely challenging to assemble. We present a novel bioinformatic data-processing pipeline called SAGBAC (Semi-Automated Graph-Based Assembly Curator) that identifies recombinogenic repeat-pairs and reconstructs plant mitochondrial genomes. SAGBAC processes assembly outputs and applies our novel ISEIS (Iterative Sequence Ends Identity Search) algorithm to obtain a graph-based visualization. We applied this approach to three mitochondrial genomes of evening primrose (Oenothera), a plant genus used for cytoplasmic genetics studies. All identified repeat pairs were found to be flanked by two alternative and unique sequence-contigs defining so-called 'double forks', resulting in four possible contig-repeat-contig combinations for each repeat pair. Based on the inferred structural models, the stoichiometry of the different contig-repeat-contig combinations was analyzed using Illumina mate-pair and PacBio RSII data. This uncovered a remarkable structural diversity of the three closely related mitochondrial genomes, as well as substantial phylogenetic variation of the underlying repeats. Our model allows predicting all recombination events and, thus, all possible sub-genomes. In future work, the proposed methodology may prove useful for the investigation of the sub-genome organization and dynamics in different tissues and at various developmental stages.
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Affiliation(s)
- Axel Fischer
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Jana Dotzek
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Dirk Walther
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Stephan Greiner
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
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16
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Choi IS, Wojciechowski MF, Steele KP, Hunter SG, Ruhlman TA, Jansen RK. Born in the mitochondrion and raised in the nucleus: evolution of a novel tandem repeat family in Medicago polymorpha (Fabaceae). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 110:389-406. [PMID: 35061308 DOI: 10.1111/tpj.15676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
Plant nuclear genomes harbor sequence elements derived from the organelles (mitochondrion and plastid) through intracellular gene transfer (IGT). Nuclear genomes also show a dramatic range of repeat content, suggesting that any sequence can be readily amplified. These two aspects of plant nuclear genomes are well recognized but have rarely been linked. Through investigation of 31 Medicago taxa we detected exceptionally high post-IGT amplification of mitochondrial (mt) DNA sequences containing rps10 in the nuclear genome of Medicago polymorpha and closely related species. The amplified sequences were characterized as tandem arrays of five distinct repeat motifs (2157, 1064, 987, 971, and 587 bp) that have diverged from the mt genome (mitogenome) in the M. polymorpha nuclear genome. The mt rps10-like arrays were identified in seven loci (six intergenic and one telomeric) of the nuclear chromosome assemblies and were the most abundant tandem repeat family, representing 1.6-3.0% of total genomic DNA, a value approximately three-fold greater than the entire mitogenome in M. polymorpha. Compared to a typical mt gene, the mt rps10-like sequence coverage level was 691.5-7198-fold higher in M. polymorpha and closely related species. In addition to the post-IGT amplification, our analysis identified the canonical telomeric repeat and the species-specific satellite arrays that are likely attributable to an ancestral chromosomal fusion in M. polymorpha. A possible relationship between chromosomal instability and the mt rps10-like tandem repeat family in the M. polymorpha clade is discussed.
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Affiliation(s)
- In-Su Choi
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | | | - Kelly P Steele
- Division of Science and Mathematics, Arizona State University, Mesa, AZ, 85212, USA
| | - Sarah G Hunter
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Tracey A Ruhlman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Robert K Jansen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- Centre of Excellence in Bionanoscience Research, Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
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17
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Smith DR. Genome evolution: Minicircular mtDNA and unusual heteroplasmy in a parasitic plant. Curr Biol 2022; 32:R86-R89. [DOI: 10.1016/j.cub.2021.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Jackman SD, Coombe L, Warren RL, Kirk H, Trinh E, MacLeod T, Pleasance S, Pandoh P, Zhao Y, Coope RJ, Bousquet J, Bohlmann J, Jones SJM, Birol I. Complete Mitochondrial Genome of a Gymnosperm, Sitka Spruce (Picea sitchensis), Indicates a Complex Physical Structure. Genome Biol Evol 2021; 12:1174-1179. [PMID: 32449750 PMCID: PMC7486957 DOI: 10.1093/gbe/evaa108] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2020] [Indexed: 12/12/2022] Open
Abstract
Plant mitochondrial genomes vary widely in size. Although many plant mitochondrial genomes have been sequenced and assembled, the vast majority are of angiosperms, and few are of gymnosperms. Most plant mitochondrial genomes are smaller than a megabase, with a few notable exceptions. We have sequenced and assembled the complete 5.5-Mb mitochondrial genome of Sitka spruce (Picea sitchensis), to date, one of the largest mitochondrial genomes of a gymnosperm. We sequenced the whole genome using Oxford Nanopore MinION, and then identified contigs of mitochondrial origin assembled from these long reads based on sequence homology to the white spruce mitochondrial genome. The assembly graph shows a multipartite genome structure, composed of one smaller 168-kb circular segment of DNA, and a larger 5.4-Mb single component with a branching structure. The assembly graph gives insight into a putative complex physical genome structure, and its branching points may represent active sites of recombination.
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Affiliation(s)
- Shaun D Jackman
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Lauren Coombe
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - René L Warren
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Heather Kirk
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Eva Trinh
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Tina MacLeod
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Stephen Pleasance
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Pawan Pandoh
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Yongjun Zhao
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Robin J Coope
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Jean Bousquet
- Forest Genomics, Institute for Systems and Integrative Biology, Université Laval, Quebec, Quebec, Canada
| | - Joerg Bohlmann
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Steven J M Jones
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
| | - Inanc Birol
- Genome Sciences Centre, BC Cancer, Vancouver, British Columbia, Canada
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19
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Mitochondrial Genomic Landscape: A Portrait of the Mitochondrial Genome 40 Years after the First Complete Sequence. Life (Basel) 2021; 11:life11070663. [PMID: 34357035 PMCID: PMC8303319 DOI: 10.3390/life11070663] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/02/2021] [Accepted: 07/03/2021] [Indexed: 12/11/2022] Open
Abstract
Notwithstanding the initial claims of general conservation, mitochondrial genomes are a largely heterogeneous set of organellar chromosomes which displays a bewildering diversity in terms of structure, architecture, gene content, and functionality. The mitochondrial genome is typically described as a single chromosome, yet many examples of multipartite genomes have been found (for example, among sponges and diplonemeans); the mitochondrial genome is typically depicted as circular, yet many linear genomes are known (for example, among jellyfish, alveolates, and apicomplexans); the chromosome is normally said to be “small”, yet there is a huge variation between the smallest and the largest known genomes (found, for example, in ctenophores and vascular plants, respectively); even the gene content is highly unconserved, ranging from the 13 oxidative phosphorylation-related enzymatic subunits encoded by animal mitochondria to the wider set of mitochondrial genes found in jakobids. In the present paper, we compile and describe a large database of 27,873 mitochondrial genomes currently available in GenBank, encompassing the whole eukaryotic domain. We discuss the major features of mitochondrial molecular diversity, with special reference to nucleotide composition and compositional biases; moreover, the database is made publicly available for future analyses on the MoZoo Lab GitHub page.
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20
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Feng Y, Xiang X, Akhter D, Pan R, Fu Z, Jin X. Mitochondrial Phylogenomics of Fagales Provides Insights Into Plant Mitogenome Mosaic Evolution. FRONTIERS IN PLANT SCIENCE 2021; 12:762195. [PMID: 34733309 PMCID: PMC8558628 DOI: 10.3389/fpls.2021.762195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 09/17/2021] [Indexed: 05/13/2023]
Abstract
Fagales are an order of woody plants and comprise more than 1,100 species, most of which produce economically important timbers, nuts, and fruits. Their nuclear and plastid genomes are well-sequenced and provided valuable resources to study their phylogeny, breeding, resistance, etc. However, little is known about the mitochondrial genomes (mitogenomes), which hinder a full understanding of their genome evolution. In this study, we assembled complete mitogenomes of 23 species, covering five of the seven families of Fagales. These mitogenomes had similar gene sets but varied 2.4 times in size. The mitochondrial genes were highly conserved, and their capacity in phylogeny was challenging. The mitogenomic structure was extremely dynamic, and synteny among species was poor. Further analyses of the Fagales mitogenomes revealed extremely mosaic characteristics, with horizontal transfer (HGT)-like sequences from almost all seed plant taxa and even mitoviruses. The largest mitogenome, Carpinus cordata, did not have large amounts of specific sequences but instead contained a high proportion of sequences homologous to other Fagales. Independent and unequal transfers of third-party DNA, including nuclear genome and other resources, may partially account for the HGT-like fragments and unbalanced size expansions observed in Fagales mitogenomes. Supporting this, a mitochondrial plasmid-like of nuclear origin was found in Carpinus. Overall, we deciphered the last genetic materials of Fagales, and our large-scale analyses provide new insights into plant mitogenome evolution and size variation.
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Affiliation(s)
- Yanlei Feng
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, China
- College of Agriculture and Biotechnology, Institute of Crop Science, Zhejiang University, Hangzhou, China
- School of Life Sciences, Westlake University, Hangzhou, China
- Yanlei Feng
| | - Xiaoguo Xiang
- School of Life Sciences, Nanchang University, Nanchang, China
| | - Delara Akhter
- College of Agriculture and Biotechnology, Institute of Crop Science, Zhejiang University, Hangzhou, China
- Department of Genetics and Plant Breeding, Sylhet Agricultural University, Sylhet, Bangladesh
| | - Ronghui Pan
- College of Agriculture and Biotechnology, Institute of Crop Science, Zhejiang University, Hangzhou, China
| | - Zhixi Fu
- College of Life Science, Sichuan Normal University, Chengdu, China
- Sustainable Development Research Center of Resources and Environment of Western Sichuan, Sichuan Normal University, Chengdu, China
- *Correspondence: Zhixi Fu
| | - Xiaohua Jin
- Institute of Botany, The Chinese Academy of Sciences, Beijing, China
- Xiaohua Jin
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21
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Peralta-Castro A, García-Medel PL, Baruch-Torres N, Trasviña-Arenas CH, Juarez-Quintero V, Morales-Vazquez CM, Brieba LG. Plant Organellar DNA Polymerases Evolved Multifunctionality through the Acquisition of Novel Amino Acid Insertions. Genes (Basel) 2020; 11:genes11111370. [PMID: 33228188 PMCID: PMC7699545 DOI: 10.3390/genes11111370] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/15/2020] [Accepted: 11/17/2020] [Indexed: 12/20/2022] Open
Abstract
The majority of DNA polymerases (DNAPs) are specialized enzymes with specific roles in DNA replication, translesion DNA synthesis (TLS), or DNA repair. The enzymatic characteristics to perform accurate DNA replication are in apparent contradiction with TLS or DNA repair abilities. For instance, replicative DNAPs incorporate nucleotides with high fidelity and processivity, whereas TLS DNAPs are low-fidelity polymerases with distributive nucleotide incorporation. Plant organelles (mitochondria and chloroplast) are replicated by family-A DNA polymerases that are both replicative and TLS DNAPs. Furthermore, plant organellar DNA polymerases from the plant model Arabidopsis thaliana (AtPOLIs) execute repair of double-stranded breaks by microhomology-mediated end-joining and perform Base Excision Repair (BER) using lyase and strand-displacement activities. AtPOLIs harbor three unique insertions in their polymerization domain that are associated with TLS, microhomology-mediated end-joining (MMEJ), strand-displacement, and lyase activities. We postulate that AtPOLIs are able to execute those different functions through the acquisition of these novel amino acid insertions, making them multifunctional enzymes able to participate in DNA replication and DNA repair.
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Affiliation(s)
- Antolín Peralta-Castro
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Paola L. García-Medel
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Noe Baruch-Torres
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Carlos H. Trasviña-Arenas
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
- Department of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616, USA
| | - Víctor Juarez-Quintero
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Carlos M. Morales-Vazquez
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Luis G. Brieba
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
- Correspondence: ; Tel.: +52-462-1663007
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Mader M, Schroeder H, Schott T, Schöning-Stierand K, Leite Montalvão AP, Liesebach H, Liesebach M, Fussi B, Kersten B. Mitochondrial Genome of Fagus sylvatica L. as a Source for Taxonomic Marker Development in the Fagales. PLANTS (BASEL, SWITZERLAND) 2020; 9:E1274. [PMID: 32992588 PMCID: PMC7650814 DOI: 10.3390/plants9101274] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 11/16/2022]
Abstract
European beech, Fagus sylvatica L., is one of the most important and widespread deciduous tree species in Central Europe and is widely managed for its hard wood. The complete DNA sequence of the mitochondrial genome of Fagus sylvatica L. was assembled and annotated based on Illumina MiSeq reads and validated using long reads from nanopore MinION sequencing. The genome assembled into a single DNA sequence of 504,715 bp in length containing 58 genes with predicted function, including 35 protein-coding, 20 tRNA and three rRNA genes. Additionally, 23 putative protein-coding genes were predicted supported by RNA-Seq data. Aiming at the development of taxon-specific mitochondrial genetic markers, the tool SNPtax was developed and applied to select genic SNPs potentially specific for different taxa within the Fagales. Further validation of a small SNP set resulted in the development of four CAPS markers specific for Fagus, Fagaceae, or Fagales, respectively, when considering over 100 individuals from a total of 69 species of deciduous trees and conifers from up to 15 families included in the marker validation. The CAPS marker set is suitable to identify the genus Fagus in DNA samples from tree tissues or wood products, including wood composite products.
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Affiliation(s)
- Malte Mader
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
| | - Hilke Schroeder
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
| | - Thomas Schott
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
| | - Katrin Schöning-Stierand
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
- Center for Bioinformatics, Universität Hamburg, 20146 Hamburg, Germany
| | - Ana Paula Leite Montalvão
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
| | - Heike Liesebach
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
| | - Mirko Liesebach
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
| | - Barbara Fussi
- Bavarian Office for Forest Genetics, 83317 Teisendorf, Germany;
| | - Birgit Kersten
- Thünen Institute of Forest Genetics, D-22927 Grosshansdorf, Germany; (M.M.); (H.S.); (T.S.); (K.S.-S.); (A.P.L.M.); (H.L.); (M.L.)
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The Tempo and Mode of Angiosperm Mitochondrial Genome Divergence Inferred from Intraspecific Variation in Arabidopsis thaliana. G3-GENES GENOMES GENETICS 2020; 10:1077-1086. [PMID: 31964685 PMCID: PMC7056966 DOI: 10.1534/g3.119.401023] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The mechanisms of sequence divergence in angiosperm mitochondrial genomes have long been enigmatic. In particular, it is difficult to reconcile the rapid divergence of intergenic regions that can make non-coding sequences almost unrecognizable even among close relatives with the unusually high levels of sequence conservation found in genic regions. It has been hypothesized that different mutation and repair mechanisms act on genic and intergenic sequences or alternatively that mutational input is relatively constant but that selection has strikingly different effects on these respective regions. To test these alternative possibilities, we analyzed mtDNA divergence within Arabidopsis thaliana, including variants from the 1001 Genomes Project and changes accrued in published mutation accumulation (MA) lines. We found that base-substitution frequencies are relatively similar for intergenic regions and synonymous sites in coding regions, whereas indel and nonsynonymous substitutions rates are greatly depressed in coding regions, supporting a conventional model in which mutation/repair mechanisms are consistent throughout the genome but differentially filtered by selection. Most types of sequence and structural changes were undetectable in 10-generation MA lines, but we found significant shifts in relative copy number across mtDNA regions for lines grown under stressed vs. benign conditions. We confirmed quantitative variation in copy number across the A. thaliana mitogenome using both whole-genome sequencing and droplet digital PCR, further undermining the classic but oversimplified model of a circular angiosperm mtDNA structure. Our results suggest that copy number variation is one of the most fluid features of angiosperm mitochondrial genomes.
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Wynn E, Purfeerst E, Christensen A. Mitochondrial DNA Repair in an Arabidopsis thaliana Uracil N-Glycosylase Mutant. PLANTS (BASEL, SWITZERLAND) 2020; 9:E261. [PMID: 32085412 PMCID: PMC7076443 DOI: 10.3390/plants9020261] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 02/07/2023]
Abstract
Substitution rates in plant mitochondrial genes are extremely low, indicating strong selective pressure as well as efficient repair. Plant mitochondria possess base excision repair pathways; however, many repair pathways such as nucleotide excision repair and mismatch repair appear to be absent. In the absence of these pathways, many DNA lesions must be repaired by a different mechanism. To test the hypothesis that double-strand break repair (DSBR) is that mechanism, we maintained independent self-crossing lineages of plants deficient in uracil-N-glycosylase (UNG) for 11 generations to determine the repair outcomes when that pathway is missing. Surprisingly, no single nucleotide polymorphisms (SNPs) were fixed in any line in generation 11. The pattern of heteroplasmic SNPs was also unaltered through 11 generations. When the rate of cytosine deamination was increased by mitochondrial expression of the cytosine deaminase APOBEC3G, there was an increase in heteroplasmic SNPs but only in mature leaves. Clearly, DNA maintenance in reproductive meristem mitochondria is very effective in the absence of UNG while mitochondrial genomes in differentiated tissue are maintained through a different mechanism or not at all. Several genes involved in DSBR are upregulated in the absence of UNG, indicating that double-strand break repair is a general system of repair in plant mitochondria. It is important to note that the developmental stage of tissues is critically important for these types of experiments.
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Affiliation(s)
- Emily Wynn
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (E.W.); (E.P.)
- United States Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, Clay Center, NE 68933, USA
| | - Emma Purfeerst
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (E.W.); (E.P.)
- Athletics Department, Bethany Lutheran College, Mankato, MN 56001, USA
| | - Alan Christensen
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (E.W.); (E.P.)
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Chevigny N, Schatz-Daas D, Lotfi F, Gualberto JM. DNA Repair and the Stability of the Plant Mitochondrial Genome. Int J Mol Sci 2020; 21:E328. [PMID: 31947741 PMCID: PMC6981420 DOI: 10.3390/ijms21010328] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/27/2019] [Accepted: 01/01/2020] [Indexed: 12/13/2022] Open
Abstract
The mitochondrion stands at the center of cell energy metabolism. It contains its own genome, the mtDNA, that is a relic of its prokaryotic symbiotic ancestor. In plants, the mitochondrial genetic information influences important agronomic traits including fertility, plant vigor, chloroplast function, and cross-compatibility. Plant mtDNA has remarkable characteristics: It is much larger than the mtDNA of other eukaryotes and evolves very rapidly in structure. This is because of recombination activities that generate alternative mtDNA configurations, an important reservoir of genetic diversity that promotes rapid mtDNA evolution. On the other hand, the high incidence of ectopic recombination leads to mtDNA instability and the expression of gene chimeras, with potential deleterious effects. In contrast to the structural plasticity of the genome, in most plant species the mtDNA coding sequences evolve very slowly, even if the organization of the genome is highly variable. Repair mechanisms are probably responsible for such low mutation rates, in particular repair by homologous recombination. Herein we review some of the characteristics of plant organellar genomes and of the repair pathways found in plant mitochondria. We further discuss how homologous recombination is involved in the evolution of the plant mtDNA.
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Affiliation(s)
| | | | | | - José Manuel Gualberto
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67081 Strasbourg, France; (N.C.); (D.S.-D.); (F.L.)
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26
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Brieba LG. Structure-Function Analysis Reveals the Singularity of Plant Mitochondrial DNA Replication Components: A Mosaic and Redundant System. PLANTS 2019; 8:plants8120533. [PMID: 31766564 PMCID: PMC6963530 DOI: 10.3390/plants8120533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Plants are sessile organisms, and their DNA is particularly exposed to damaging agents. The integrity of plant mitochondrial and plastid genomes is necessary for cell survival. During evolution, plants have evolved mechanisms to replicate their mitochondrial genomes while minimizing the effects of DNA damaging agents. The recombinogenic character of plant mitochondrial DNA, absence of defined origins of replication, and its linear structure suggest that mitochondrial DNA replication is achieved by a recombination-dependent replication mechanism. Here, I review the mitochondrial proteins possibly involved in mitochondrial DNA replication from a structural point of view. A revision of these proteins supports the idea that mitochondrial DNA replication could be replicated by several processes. The analysis indicates that DNA replication in plant mitochondria could be achieved by a recombination-dependent replication mechanism, but also by a replisome in which primers are synthesized by three different enzymes: Mitochondrial RNA polymerase, Primase-Helicase, and Primase-Polymerase. The recombination-dependent replication model and primers synthesized by the Primase-Polymerase may be responsible for the presence of genomic rearrangements in plant mitochondria.
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Affiliation(s)
- Luis Gabriel Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato C.P. 36821, Mexico
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27
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García-Medel PL, Baruch-Torres N, Peralta-Castro A, Trasviña-Arenas CH, Torres-Larios A, Brieba LG. Plant organellar DNA polymerases repair double-stranded breaks by microhomology-mediated end-joining. Nucleic Acids Res 2019; 47:3028-3044. [PMID: 30698803 PMCID: PMC6451138 DOI: 10.1093/nar/gkz039] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 12/23/2018] [Accepted: 01/15/2019] [Indexed: 12/27/2022] Open
Abstract
Double-stranded breaks (DSBs) in plant organelles are repaired via genomic rearrangements characterized by microhomologous repeats. These microhomologous signatures predict the existence of an unidentified enzymatic machinery capable of repairing of DSBs via microhomology-mediated end-joining (MMEJ) in plant organelles. Here, we show that organellar DNA polymerases from Arabidopsis thaliana (AtPolIA and AtPolIB) perform MMEJ using microhomologous sequences as short as six nucleotides. AtPolIs execute MMEJ by virtue of two specialized amino acid insertions located in their thumb subdomains. Single-stranded binding proteins (SSBs) unique to plants, AtWhirly2 and organellar single-stranded binding proteins (AtOSBs), hinder MMEJ, whereas canonical mitochondrial SSBs (AtmtSSB1 and AtmtSSB2) do not interfere with MMEJ. Our data predict that organellar DNA rearrangements by MMEJ are a consequence of a competition for the 3'-OH of a DSBs. If AtWhirlies or AtOSBs gain access to the single-stranded DNA (ssDNA) region of a DSB, the reaction will shift towards high-fidelity routes like homologous recombination. Conversely MMEJ would be favored if AtPolIs or AtmtSSBs interact with the DSB. AtPolIs are not phylogenetically related to metazoan mitochondrial DNA polymerases, and the ability of AtPolIs to execute MMEJ may explain the abundance of DNA rearrangements in plant organelles in comparison to animal mitochondria.
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Affiliation(s)
- Paola L García-Medel
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato, CP 36821, México
| | - Noe Baruch-Torres
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato, CP 36821, México
| | - Antolín Peralta-Castro
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato, CP 36821, México
| | - Carlos H Trasviña-Arenas
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato, CP 36821, México
| | - Alfredo Torres-Larios
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, Apartado postal 70-243, Mexico City 04510, México
| | - Luis G Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato, CP 36821, México
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Lloyd Evans D, Hlongwane TT, Joshi SV, Riaño Pachón DM. The sugarcane mitochondrial genome: assembly, phylogenetics and transcriptomics. PeerJ 2019; 7:e7558. [PMID: 31579570 PMCID: PMC6764373 DOI: 10.7717/peerj.7558] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 07/26/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Chloroplast genomes provide insufficient phylogenetic information to distinguish between closely related sugarcane cultivars, due to the recent origin of many cultivars and the conserved sequence of the chloroplast. In comparison, the mitochondrial genome of plants is much larger and more plastic and could contain increased phylogenetic signals. We assembled a consensus reference mitochondrion with Illumina TruSeq synthetic long reads and Oxford Nanopore Technologies MinION long reads. Based on this assembly we also analyzed the mitochondrial transcriptomes of sugarcane and sorghum and improved the annotation of the sugarcane mitochondrion as compared with other species. METHODS Mitochondrial genomes were assembled from genomic read pools using a bait and assemble methodology. The mitogenome was exhaustively annotated using BLAST and transcript datasets were mapped with HISAT2 prior to analysis with the Integrated Genome Viewer. RESULTS The sugarcane mitochondrion is comprised of two independent chromosomes, for which there is no evidence of recombination. Based on the reference assembly from the sugarcane cultivar SP80-3280 the mitogenomes of four additional cultivars (R570, LCP85-384, RB72343 and SP70-1143) were assembled (with the SP70-1143 assembly utilizing both genomic and transcriptomic data). We demonstrate that the sugarcane plastome is completely transcribed and we assembled the chloroplast genome of SP80-3280 using transcriptomic data only. Phylogenomic analysis using mitogenomes allow closely related sugarcane cultivars to be distinguished and supports the discrimination between Saccharum officinarum and Saccharum cultum as modern sugarcane's female parent. From whole chloroplast comparisons, we demonstrate that modern sugarcane arose from a limited number of Saccharum cultum female founders. Transcriptomic and spliceosomal analyses reveal that the two chromosomes of the sugarcane mitochondrion are combined at the transcript level and that splice sites occur more frequently within gene coding regions than without. We reveal one confirmed and one potential cytoplasmic male sterility (CMS) factor in the sugarcane mitochondrion, both of which are transcribed. CONCLUSION Transcript processing in the sugarcane mitochondrion is highly complex with diverse splice events, the majority of which span the two chromosomes. PolyA baited transcripts are consistent with the use of polyadenylation for transcript degradation. For the first time we annotate two CMS factors within the sugarcane mitochondrion and demonstrate that sugarcane possesses all the molecular machinery required for CMS and rescue. A mechanism of cross-chromosomal splicing based on guide RNAs is proposed. We also demonstrate that mitogenomes can be used to perform phylogenomic studies on sugarcane cultivars.
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Affiliation(s)
- Dyfed Lloyd Evans
- Plant Breeding, South African Sugarcane Research Institute, Durban, KwaZulu-Natal, South Africa
- Cambridge Sequence Services (CSS), Waterbeach, Cambridgeshire, UK
- Department of Computer Sciences, Université Cheikh Anta Diop de Dakar, Dakar, Sénégal
| | | | - Shailesh V. Joshi
- Plant Breeding, South African Sugarcane Research Institute, Durban, KwaZulu-Natal, South Africa
- School of Life Sciences, College of Agriculture Engineering and Science, University of KwaZulu-Natal, Durban, KwaZulu-Natal, South Africa
| | - Diego M. Riaño Pachón
- Computational, Evolutionary and Systems Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil
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29
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Plant Organelle Genome Replication. PLANTS 2019; 8:plants8100358. [PMID: 31546578 PMCID: PMC6843274 DOI: 10.3390/plants8100358] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/14/2019] [Accepted: 09/18/2019] [Indexed: 12/21/2022]
Abstract
Mitochondria and chloroplasts perform essential functions in respiration, ATP production, and photosynthesis, and both organelles contain genomes that encode only some of the proteins that are required for these functions. The proteins and mechanisms for organelle DNA replication are very similar to bacterial or phage systems. The minimal replisome may consist of DNA polymerase, a primase/helicase, and a single-stranded DNA binding protein (SSB), similar to that found in bacteriophage T7. In Arabidopsis, there are two genes for organellar DNA polymerases and multiple potential genes for SSB, but there is only one known primase/helicase protein to date. Genome copy number varies widely between type and age of plant tissues. Replication mechanisms are only poorly understood at present, and may involve multiple processes, including recombination-dependent replication (RDR) in plant mitochondria and perhaps also in chloroplasts. There are still important questions remaining as to how the genomes are maintained in new organelles, and how genome copy number is determined. This review summarizes our current understanding of these processes.
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30
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Kozik A, Rowan BA, Lavelle D, Berke L, Schranz ME, Michelmore RW, Christensen AC. The alternative reality of plant mitochondrial DNA: One ring does not rule them all. PLoS Genet 2019; 15:e1008373. [PMID: 31469821 PMCID: PMC6742443 DOI: 10.1371/journal.pgen.1008373] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 09/12/2019] [Accepted: 08/16/2019] [Indexed: 01/27/2023] Open
Abstract
Plant mitochondrial genomes are usually assembled and displayed as circular maps based on the widely-held view across the broad community of life scientists that circular genome-sized molecules are the primary form of plant mitochondrial DNA, despite the understanding by plant mitochondrial researchers that this is an inaccurate and outdated concept. Many plant mitochondrial genomes have one or more pairs of large repeats that can act as sites for inter- or intramolecular recombination, leading to multiple alternative arrangements (isoforms). Most mitochondrial genomes have been assembled using methods unable to capture the complete spectrum of isoforms within a species, leading to an incomplete inference of their structure and recombinational activity. To document and investigate underlying reasons for structural diversity in plant mitochondrial DNA, we used long-read (PacBio) and short-read (Illumina) sequencing data to assemble and compare mitochondrial genomes of domesticated (Lactuca sativa) and wild (L. saligna and L. serriola) lettuce species. We characterized a comprehensive, complex set of isoforms within each species and compared genome structures between species. Physical analysis of L. sativa mtDNA molecules by fluorescence microscopy revealed a variety of linear, branched, and circular structures. The mitochondrial genomes for L. sativa and L. serriola were identical in sequence and arrangement and differed substantially from L. saligna, indicating that the mitochondrial genome structure did not change during domestication. From the isoforms in our data, we infer that recombination occurs at repeats of all sizes at variable frequencies. The differences in genome structure between L. saligna and the two other Lactuca species can be largely explained by rare recombination events that rearranged the structure. Our data demonstrate that representations of plant mitochondrial genomes as simple, circular molecules are not accurate descriptions of their true nature and that in reality plant mitochondrial DNA is a complex, dynamic mixture of forms.
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Affiliation(s)
- Alexander Kozik
- Genome Center and Department of Plant Sciences, University of California, Davis, California, United States of America
| | - Beth A. Rowan
- Genome Center and Department of Plant Sciences, University of California, Davis, California, United States of America
| | - Dean Lavelle
- Genome Center and Department of Plant Sciences, University of California, Davis, California, United States of America
| | - Lidija Berke
- Wageningen University & Research, PB Wageningen, Gelderland, The Netherlands
| | - M. Eric Schranz
- Wageningen University & Research, PB Wageningen, Gelderland, The Netherlands
| | - Richard W. Michelmore
- Genome Center and Department of Plant Sciences, University of California, Davis, California, United States of America
| | - Alan C. Christensen
- School of Biological Sciences, University of Nebraska - Lincoln, Lincoln, Nebraska, United States of America
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31
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Garcia LE, Zubko MK, Zubko EI, Sanchez-Puerta MV. Elucidating genomic patterns and recombination events in plant cybrid mitochondria. PLANT MOLECULAR BIOLOGY 2019; 100:433-450. [PMID: 30968307 DOI: 10.1007/s11103-019-00869-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 04/01/2019] [Indexed: 05/17/2023]
Abstract
KEY MESSAGE Cybrid plant mitochondria undergo homologous recombination, mainly BIR, keep a single allele for each gene, and maintain exclusive sequences of each parent and a single copy of the homologous regions. The maintenance of a dynamic equilibrium between the mitochondrial and nuclear genomes requires continuous communication and a high level of compatibility between them, so that alterations in one genetic compartment need adjustments in the other. The co-evolution of nuclear and mitochondrial genomes has been poorly studied, even though the consequences and effects of this interaction are highly relevant for human health, as well as for crop improvement programs and for genetic engineering. The mitochondria of plants represent an excellent system to understand the mechanisms of genomic rearrangements, chimeric gene formation, incompatibility between nucleus and cytoplasm, and horizontal gene transfer. We carried out detailed analyses of the mtDNA of a repeated cybrid between the solanaceae Nicotiana tabacum and Hyoscyamus niger. The mtDNA of the cybrid was intermediate between the size of the parental mtDNAs and the sum of them. Noticeably, most of the homologous sequences inherited from both parents were lost. In contrast, the majority of the sequences exclusive of a single parent were maintained. The mitochondrial gene content included a majority of N. tabacum derived genes, but also chimeric, two-parent derived, and H. niger-derived genes in a tobacco nuclear background. Any of these alterations in the gene content could be the cause of CMS in the cybrid. The parental mtDNAs interacted through 28 homologous recombination events and a single case of illegitimate recombination. Three main homologous recombination mechanisms were recognized in the cybrid mitochondria. Break induced replication (BIR) pathway was the most frequent. We propose that BIR could be one of the mechanisms responsible for the loss of the majority of the repeated regions derived from H. niger.
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Affiliation(s)
- Laura E Garcia
- Facultad de Ciencias Agrarias, IBAM, Universidad Nacional de Cuyo, CONICET, Almirante Brown 500, M5528AHB, Chacras de Coria, Argentina.
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina.
| | - Mikhajlo K Zubko
- Centre for Bioscience, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, M1 5GD, UK
| | - Elena I Zubko
- Centre for Bioscience, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, M1 5GD, UK
| | - M Virginia Sanchez-Puerta
- Facultad de Ciencias Agrarias, IBAM, Universidad Nacional de Cuyo, CONICET, Almirante Brown 500, M5528AHB, Chacras de Coria, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
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Yasukawa T, Kang D. An overview of mammalian mitochondrial DNA replication mechanisms. J Biochem 2018; 164:183-193. [PMID: 29931097 PMCID: PMC6094444 DOI: 10.1093/jb/mvy058] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/15/2018] [Indexed: 11/14/2022] Open
Abstract
While the majority of DNA is enclosed within the nucleus, the mitochondria also contain their own, separate DNA, the mitochondrial DNA (mtDNA). Mutations in mtDNA are associated with various human diseases, demonstrating the importance of mtDNA. Intensive studies over the last 18 years have demonstrated the presence of two distinct classes of mtDNA replication intermediates in mammals. One involves leading-strand DNA synthesis in the absence of synchronous lagging-strand DNA synthesis. Currently there are competing models in which the lagging-strand template is either systematically hybridized to processed mitochondrial transcripts, or coated with protein, until the lagging-strand DNA synthesis takes place. The other class of mtDNA replication intermediates has many properties of conventional, coupled leading- and lagging-strand DNA synthesis. Additionally, the highly unusual arrangement of DNA in human heart mitochondria suggests a third mechanism of replication. These findings indicate that the mtDNA replication systems of humans and other mammals are far more complex than previously thought, and thereby will require further research to understand the full picture of mtDNA replication.
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Affiliation(s)
- Takehiro Yasukawa
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Japan
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Japan
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Ayala-García VM, Baruch-Torres N, García-Medel PL, Brieba LG. Plant organellar DNA polymerases paralogs exhibit dissimilar nucleotide incorporation fidelity. FEBS J 2018; 285:4005-4018. [PMID: 30152200 DOI: 10.1111/febs.14645] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/27/2018] [Accepted: 08/24/2018] [Indexed: 01/06/2023]
Abstract
The coding sequences of plant mitochondrial and chloroplast genomes present a lower mutation rate than the coding sequences of animal mitochondria. However, plant mitochondrial genomes frequently rearrange and present high mutation rates in their noncoding sequences. DNA replication in plant organelles is carried out by two DNA polymerases (DNAP) paralogs. In Arabidopsis thaliana at least one DNAP paralog (AtPolIA or AtPolIB) is necessary for plant viability, suggesting that both genes are partially redundant. To understand how AtPolIs replicate genomes that present low and high mutation rates, we measured their nucleotide incorporation for all 16-base pair combinations in vitro. AtPolIA presents an error rate of 7.26 × 10-5 , whereas AtPolIB has an error rate of 5.45 × 10-4 . Thus, AtPolIA and AtPolIB are 3.5 and 26-times less accurate than human mitochondrial DNAP γ. The 8-fold difference in fidelity between both AtPolIs results from a higher catalytic efficiency in AtPolIA. Both AtPolIs extend from mismatches and the fidelity of AtPolIs ranks between high fidelity and lesion bypass DNAPs. The different nucleotide incorporation fidelity between AtPolIs predicts a prevalent role of AtPolIA in DNA replication and AtPolIB in DNA repair. We hypothesize that in plant organelles, DNA mismatches generated during DNA replication are repaired via recombination-mediated or DNA mismatch repair mechanisms that selectively target the coding region and that the mismatches generated by AtPolIs may result in the frequent expansion and rearrangements present in plant mitochondrial genomes.
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Hameed MW, Juszczak I, Bock R, van Dongen JT. Comparison of mitochondrial gene expression and polysome loading in different tobacco tissues. PLANT METHODS 2017; 13:112. [PMID: 29255478 PMCID: PMC5729415 DOI: 10.1186/s13007-017-0257-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Accepted: 11/22/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND To investigate translational regulation of gene expression in plant mitochondria, a mitochondrial polysome isolation protocol was established for tobacco to investigate polysomal mRNA loading as a proxy for translational activity. Furthermore, we developed an oligonucleotide based microarray platform to determine the level of Nicotiana tabacum and Arabidopsis thaliana mitochondrial mRNA. RESULTS Microarray analysis of free and polysomal mRNAs was used to characterize differences in the levels of free transcripts and ribosome-bound mRNAs in various organs of tobacco plants. We have observed higher mitochondrial transcript levels in young leaves, flowers and floral buds as compared to fully expanded leaves and roots. A similar pattern of abundance was observed for ribosome-bound mitochondrial mRNAs in these tissues. However, the accumulation of the mitochondrial protein COX2 was found to be inversely related to that of its ribosome-bound mRNA. CONCLUSIONS Our results indicate that the association of mitochondrial mRNAs to ribosomes is largely determined by the total transcript level of a gene. However, at least for Cox2, we demonstrated that the level of ribosome-bound mRNA is not reflected by the amount of COX2 protein.
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Affiliation(s)
- Muhammad Waqar Hameed
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270 Pakistan
| | - Ilona Juszczak
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
- Molecular Physiology, University of Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Joost Thomas van Dongen
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
- Institute of Biology I, RWTH Aachen University, Worringerweg 1, 52056 Aachen, Germany
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Mitochondrial DNA replication: a PrimPol perspective. Biochem Soc Trans 2017; 45:513-529. [PMID: 28408491 PMCID: PMC5390496 DOI: 10.1042/bst20160162] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 12/20/2022]
Abstract
PrimPol, (primase-polymerase), the most recently identified eukaryotic polymerase, has roles in both nuclear and mitochondrial DNA maintenance. PrimPol is capable of acting as a DNA polymerase, with the ability to extend primers and also bypass a variety of oxidative and photolesions. In addition, PrimPol also functions as a primase, catalysing the preferential formation of DNA primers in a zinc finger-dependent manner. Although PrimPol's catalytic activities have been uncovered in vitro, we still know little about how and why it is targeted to the mitochondrion and what its key roles are in the maintenance of this multicopy DNA molecule. Unlike nuclear DNA, the mammalian mitochondrial genome is circular and the organelle has many unique proteins essential for its maintenance, presenting a differing environment within which PrimPol must function. Here, we discuss what is currently known about the mechanisms of DNA replication in the mitochondrion, the proteins that carry out these processes and how PrimPol is likely to be involved in assisting this vital cellular process.
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Cheng N, Lo YS, Ansari MI, Ho KC, Jeng ST, Lin NS, Dai H. Correlation between mtDNA complexity and mtDNA replication mode in developing cotyledon mitochondria during mung bean seed germination. THE NEW PHYTOLOGIST 2017; 213:751-763. [PMID: 27611966 DOI: 10.1111/nph.14158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 07/18/2016] [Indexed: 05/11/2023]
Abstract
The currently accepted model of recombination-dependent replication (RDR) in plant mitochondrial DNA (mtDNA) does not clearly explain how RDR progresses and how highly complex mtDNA develops. This study aimed to investigate the correlation between RDR and mtDNA complexity during mitochondrial development in mung bean (Vigna radiata) seed, and the initiation and processing of RDR in plant mitochondria. Flow cytometry, pulsed-field gel electrophoresis, electron microscopy, real-time PCR and biochemical studies were used in this study. The highly dynamic changes in mtDNA complexity correspond to mtDNA RDR activity throughout mitochondrial development. With in vitro freeze-thaw treatment or prolonged in vivo cold incubation, the mtDNA rosette core disappeared and the rosette structure converted to a much longer linear DNA structure. D-loops, Holliday junctions and putative RDR forks often appeared near the rosette cores. We hypothesize that the rosette core may consist of condensed mtDNA and a replication starting sequence, and play an initial and central role in RDR. The satellite cores in the rosette structure may represent the re-initiation sites of mtDNA RDR in the same parental molecule, thereby forming highly complex and giant mitochondrial molecules, representing the RDR intermediates, in vivo.
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Affiliation(s)
- Ning Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
- Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan
| | - Yih-Shan Lo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | | | - Kuo-Chieh Ho
- Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan
| | - Shih-Tong Jeng
- Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Hwa Dai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
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Tremblay-Belzile S, Lepage É, Zampini É, Brisson N. Short-range inversions: rethinking organelle genome stability: template switching events during DNA replication destabilize organelle genomes. Bioessays 2015. [PMID: 26222836 DOI: 10.1002/bies.201500064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In the organelles of plants and mammals, recent evidence suggests that genomic instability stems in large part from template switching events taking place during DNA replication. Although more than one mechanism may be responsible for this, some similarities exist between the different proposed models. These can be separated into two main categories, depending on whether they involve a single-strand-switching or a reciprocal-strand-switching event. Single-strand-switching events lead to intermediates containing Y junctions, whereas reciprocal-strand-switching creates Holliday junctions. Common features in all the described models include replication stress, fork stalling and the presence of inverted repeats, but no single element appears to be required in all cases. We review the field, and examine the ideas that several mechanisms may take place in any given genome, and that the presence of palindromes or inverted repeats in certain regions may favor specific rearrangements.
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Affiliation(s)
- Samuel Tremblay-Belzile
- Department of Biochemistry and Molecular Medicine, Universit, é, de Montréal, Montréal, Québec, Canada
| | - Étienne Lepage
- Department of Biochemistry and Molecular Medicine, Universit, é, de Montréal, Montréal, Québec, Canada
| | - Éric Zampini
- Department of Biochemistry and Molecular Medicine, Universit, é, de Montréal, Montréal, Québec, Canada
| | - Normand Brisson
- Department of Biochemistry and Molecular Medicine, Universit, é, de Montréal, Montréal, Québec, Canada
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Skippington E, Barkman TJ, Rice DW, Palmer JD. Miniaturized mitogenome of the parasitic plant Viscum scurruloideum is extremely divergent and dynamic and has lost all nad genes. Proc Natl Acad Sci U S A 2015; 112:E3515-24. [PMID: 26100885 PMCID: PMC4500244 DOI: 10.1073/pnas.1504491112] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite the enormous diversity among parasitic angiosperms in form and structure, life-history strategies, and plastid genomes, little is known about the diversity of their mitogenomes. We report the sequence of the wonderfully bizarre mitogenome of the hemiparasitic aerial mistletoe Viscum scurruloideum. This genome is only 66 kb in size, making it the smallest known angiosperm mitogenome by a factor of more than three and the smallest land plant mitogenome. Accompanying this size reduction is exceptional reduction of gene content. Much of this reduction arises from the unexpected loss of respiratory complex I (NADH dehydrogenase), universally present in all 300+ other angiosperms examined, where it is encoded by nine mitochondrial and many nuclear nad genes. Loss of complex I in a multicellular organism is unprecedented. We explore the potential relationship between this loss in Viscum and its parasitic lifestyle. Despite its small size, the Viscum mitogenome is unusually rich in recombinationally active repeats, possessing unparalleled levels of predicted sublimons resulting from recombination across short repeats. Many mitochondrial gene products exhibit extraordinary levels of divergence in Viscum, indicative of highly relaxed if not positive selection. In addition, all Viscum mitochondrial protein genes have experienced a dramatic acceleration in synonymous substitution rates, consistent with the hypothesis of genomic streamlining in response to a high mutation rate but completely opposite to the pattern seen for the high-rate but enormous mitogenomes of Silene. In sum, the Viscum mitogenome possesses a unique constellation of extremely unusual features, a subset of which may be related to its parasitic lifestyle.
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Affiliation(s)
| | - Todd J Barkman
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008
| | - Danny W Rice
- Department of Biology, Indiana University, Bloomington, IN 47405
| | - Jeffrey D Palmer
- Department of Biology, Indiana University, Bloomington, IN 47405;
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39
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Kumar RA, Oldenburg DJ, Bendich AJ. Changes in DNA damage, molecular integrity, and copy number for plastid DNA and mitochondrial DNA during maize development. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:6425-39. [PMID: 25261192 PMCID: PMC4246179 DOI: 10.1093/jxb/eru359] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The amount and structural integrity of organellar DNAs change during plant development, although the mechanisms of change are poorly understood. Using PCR-based methods, we quantified DNA damage, molecular integrity, and genome copy number for plastid and mitochondrial DNAs of maize seedlings. A DNA repair assay was also used to assess DNA impediments. During development, DNA damage increased and molecules with impediments that prevented amplification by Taq DNA polymerase increased, with light causing the greatest change. DNA copy number values depended on the assay method, with standard real-time quantitative PCR (qPCR) values exceeding those determined by long-PCR by 100- to 1000-fold. As the organelles develop, their DNAs may be damaged in oxidative environments created by photo-oxidative reactions and photosynthetic/respiratory electron transfer. Some molecules may be repaired, while molecules with unrepaired damage may be degraded to non-functional fragments measured by standard qPCR but not by long-PCR.
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Affiliation(s)
- Rachana A Kumar
- Department of Biology, University of Washington, Seattle, WA 98195-5325, USA
| | - Delene J Oldenburg
- Department of Biology, University of Washington, Seattle, WA 98195-5325, USA
| | - Arnold J Bendich
- Department of Biology, University of Washington, Seattle, WA 98195-5325, USA
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40
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Cupp JD, Nielsen BL. Minireview: DNA replication in plant mitochondria. Mitochondrion 2014; 19 Pt B:231-7. [PMID: 24681310 PMCID: PMC4177014 DOI: 10.1016/j.mito.2014.03.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 02/28/2014] [Accepted: 03/19/2014] [Indexed: 10/25/2022]
Abstract
Higher plant mitochondrial genomes exhibit much greater structural complexity compared to most other organisms. Unlike well-characterized metazoan mitochondrial DNA (mtDNA) replication, an understanding of the mechanism(s) and proteins involved in plant mtDNA replication remains unclear. Several plant mtDNA replication proteins, including DNA polymerases, DNA primase/helicase, and accessory proteins have been identified. Mitochondrial dynamics, genome structure, and the complexity of dual-targeted and dual-function proteins that provide at least partial redundancy suggest that plants have a unique model for maintaining and replicating mtDNA when compared to the replication mechanism utilized by most metazoan organisms.
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Affiliation(s)
- John D Cupp
- Department of Microbiology & Molecular Biology, Brigham Young University, Provo, UT 84602, United States.
| | - Brent L Nielsen
- Department of Microbiology & Molecular Biology, Brigham Young University, Provo, UT 84602, United States.
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41
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Gerhold JM, Sedman T, Visacka K, Slezakova J, Tomaska L, Nosek J, Sedman J. Replication intermediates of the linear mitochondrial DNA of Candida parapsilosis suggest a common recombination based mechanism for yeast mitochondria. J Biol Chem 2014; 289:22659-22670. [PMID: 24951592 DOI: 10.1074/jbc.m114.552828] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Variation in the topology of mitochondrial DNA (mtDNA) in eukaryotes evokes the question if differently structured DNAs are replicated by a common mechanism. RNA-primed DNA synthesis has been established as a mechanism for replicating the circular animal/mammalian mtDNA. In yeasts, circular mtDNA molecules were assumed to be templates for rolling circle DNA-replication. We recently showed that in Candida albicans, which has circular mapping mtDNA, recombination driven replication is a major mechanism for replicating a complex branched mtDNA network. Careful analyses of C. albicans-mtDNA did not reveal detectable amounts of circular DNA molecules. In the present study we addressed the question of how the unit sized linear mtDNA of Candida parapsilosis terminating at both ends with arrays of tandem repeats (mitochondrial telomeres) is replicated. Originally, we expected to find replication intermediates diagnostic of canonical bi-directional replication initiation at the centrally located bi-directional promoter region. However, we found that the linear mtDNA of Candida parapsilosis also employs recombination for replication initiation. The most striking findings were that the mitochondrial telomeres appear to be hot spots for recombination driven replication, and that stable RNA:DNA hybrids, with a potential role in mtDNA replication, are also present in the mtDNA preparations.
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Affiliation(s)
- Joachim M Gerhold
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23c, 51014 Tartu, Estonia and.
| | - Tiina Sedman
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23c, 51014 Tartu, Estonia and
| | - Katarina Visacka
- Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-1, and
| | - Judita Slezakova
- Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-1, and
| | - Lubomir Tomaska
- Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-1, and
| | - Jozef Nosek
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina CH-1, 842 15 Bratislava, Slovak Republic
| | - Juhan Sedman
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23c, 51014 Tartu, Estonia and
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42
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Mechanism of homologous recombination and implications for aging-related deletions in mitochondrial DNA. Microbiol Mol Biol Rev 2014; 77:476-96. [PMID: 24006472 DOI: 10.1128/mmbr.00007-13] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Homologous recombination is a universal process, conserved from bacteriophage to human, which is important for the repair of double-strand DNA breaks. Recombination in mitochondrial DNA (mtDNA) was documented more than 4 decades ago, but the underlying molecular mechanism has remained elusive. Recent studies have revealed the presence of a Rad52-type recombination system of bacteriophage origin in mitochondria, which operates by a single-strand annealing mechanism independent of the canonical RecA/Rad51-type recombinases. Increasing evidence supports the notion that, like in bacteriophages, mtDNA inheritance is a coordinated interplay between recombination, repair, and replication. These findings could have profound implications for understanding the mechanism of mtDNA inheritance and the generation of mtDNA deletions in aging cells.
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43
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Sloan DB. One ring to rule them all? Genome sequencing provides new insights into the 'master circle' model of plant mitochondrial DNA structure. THE NEW PHYTOLOGIST 2013; 200:978-85. [PMID: 24712049 DOI: 10.1111/nph.12395] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The in vivo molecular structure of plant mitochondrial DNA (mtDNA) has been a long-standing source of intrigue and controversy. Recent deep sequencing analyses of mitochondrial genomes from numerous plant species have provided the opportunity to revisit this decades-old question from a novel perspective. Whole-genome sequencing approaches have yielded new lines of evidence that the 'master circle' is not the predominant form of plant mtDNA and have revealed striking structural variation both within and among species. Here, I review these recent studies,including the discovery that at least two independent angiosperm lineages have evolved multichromosomal mitochondrial genome structures. These findings raise fascinating questions regarding the mechanisms of plant mtDNA replication and inheritance.
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44
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Gualberto JM, Mileshina D, Wallet C, Niazi AK, Weber-Lotfi F, Dietrich A. The plant mitochondrial genome: dynamics and maintenance. Biochimie 2013; 100:107-20. [PMID: 24075874 DOI: 10.1016/j.biochi.2013.09.016] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/17/2013] [Indexed: 12/21/2022]
Abstract
Plant mitochondria have a complex and peculiar genetic system. They have the largest genomes, as compared to organelles from other eukaryotic organisms. These can expand tremendously in some species, reaching the megabase range. Nevertheless, whichever the size, the gene content remains modest and restricted to a few polypeptides required for the biogenesis of the oxidative phosphorylation chain complexes, ribosomal proteins, transfer RNAs and ribosomal RNAs. The presence of autonomous plasmids of essentially unknown function further enhances the level of complexity. The physical organization of the plant mitochondrial DNA includes a set of sub-genomic forms resulting from homologous recombination between repeats, with a mixture of linear, circular and branched structures. This material is compacted into membrane-bound nucleoids, which are the inheritance units but also the centers of genome maintenance and expression. Recombination appears to be an essential characteristic of plant mitochondrial genetic processes, both in shaping and maintaining the genome. Under nuclear surveillance, recombination is also the basis for the generation of new mitotypes and is involved in the evolution of the mitochondrial DNA. In line with, or as a consequence of its complex physical organization, replication of the plant mitochondrial DNA is likely to occur through multiple mechanisms, potentially involving recombination processes. We give here a synthetic view of these aspects.
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Affiliation(s)
- José M Gualberto
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Daria Mileshina
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Clémentine Wallet
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Adnan Khan Niazi
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Frédérique Weber-Lotfi
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - André Dietrich
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
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Negruk V. Mitochondrial Genome Sequence of the Legume Vicia faba. FRONTIERS IN PLANT SCIENCE 2013; 4:128. [PMID: 23675376 PMCID: PMC3646248 DOI: 10.3389/fpls.2013.00128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 04/19/2013] [Indexed: 05/26/2023]
Abstract
The number of plant mitochondrial genomes sequenced exceeds two dozen. However, for a detailed comparative study of different phylogenetic branches more plant mitochondrial genomes should be sequenced. This article presents sequencing data and comparative analysis of mitochondrial DNA (mtDNA) of the legume Vicia faba. The size of the V. faba circular mitochondrial master chromosome of cultivar Broad Windsor was estimated as 588,000 bp with a genome complexity of 387,745 bp and 52 conservative mitochondrial genes; 32 of them encoding proteins, 3 rRNA, and 17 tRNA genes. Six tRNA genes were highly homologous to chloroplast genome sequences. In addition to the 52 conservative genes, 114 unique open reading frames (ORFs) were found, 36 without significant homology to any known proteins and 29 with homology to the Medicago truncatula nuclear genome and to other plant mitochondrial ORFs, 49 ORFs were not homologous to M. truncatula but possessed sequences with significant homology to other plant mitochondrial or nuclear ORFs. In general, the unique ORFs revealed very low homology to known closely related legumes, but several sequence homologies were found between V. faba, Beta vulgaris, Nicotiana tabacum, Vitis vinifera, and even the monocots Oryza sativa and Zea mays. Most likely these ORFs arose independently during angiosperm evolution (Kubo and Mikami, 2007; Kubo and Newton, 2008). Computational analysis revealed in total about 45% of V. faba mtDNA sequence being homologous to the Medicago truncatula nuclear genome (more than to any sequenced plant mitochondrial genome), and 35% of this homology ranging from a few dozen to 12,806 bp are located on chromosome 1. Apparently, mitochondrial rrn5, rrn18, rps10, ATP synthase subunit alpha, cox2, and tRNA sequences are part of transcribed nuclear mosaic ORFs.
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Diray-Arce J, Liu B, Cupp JD, Hunt T, Nielsen BL. The Arabidopsis At1g30680 gene encodes a homologue to the phage T7 gp4 protein that has both DNA primase and DNA helicase activities. BMC PLANT BIOLOGY 2013; 13:36. [PMID: 23452619 PMCID: PMC3610141 DOI: 10.1186/1471-2229-13-36] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 02/26/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND The Arabidopsis thaliana genome encodes a homologue of the full-length bacteriophage T7 gp4 protein, which is also homologous to the eukaryotic Twinkle protein. While the phage protein has both DNA primase and DNA helicase activities, in animal cells Twinkle is localized to mitochondria and has only DNA helicase activity due to sequence changes in the DNA primase domain. However, Arabidopsis and other plant Twinkle homologues retain sequence homology for both functional domains of the phage protein. The Arabidopsis Twinkle homologue has been shown by others to be dual targeted to mitochondria and chloroplasts. RESULTS To determine the functional activity of the Arabidopsis protein we obtained the gene for the full-length Arabidopsis protein and expressed it in bacteria. The purified protein was shown to have both DNA primase and DNA helicase activities. Western blot and qRT-PCR analysis indicated that the Arabidopsis gene is expressed most abundantly in young leaves and shoot apex tissue, as expected if this protein plays a role in organelle DNA replication. This expression is closely correlated with the expression of organelle-localized DNA polymerase in the same tissues. Homologues from other plant species show close similarity by phylogenetic analysis. CONCLUSIONS The results presented here indicate that the Arabidopsis phage T7 gp4/Twinkle homologue has both DNA primase and DNA helicase activities and may provide these functions for organelle DNA replication.
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Affiliation(s)
- Joann Diray-Arce
- Dept. of Microbiology & Molecular Biology, 775 WIDB, Brigham Young University, Provo, Utah, 84602, USA
| | - Bin Liu
- Dept. of Microbiology & Molecular Biology, 775 WIDB, Brigham Young University, Provo, Utah, 84602, USA
| | - John D Cupp
- Dept. of Microbiology & Molecular Biology, 775 WIDB, Brigham Young University, Provo, Utah, 84602, USA
| | - Travis Hunt
- Dept. of Microbiology & Molecular Biology, 775 WIDB, Brigham Young University, Provo, Utah, 84602, USA
| | - Brent L Nielsen
- Dept. of Microbiology & Molecular Biology, 775 WIDB, Brigham Young University, Provo, Utah, 84602, USA
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Oldenburg DJ, Kumar RA, Bendich AJ. The amount and integrity of mtDNA in maize decline with development. PLANTA 2013; 237:603-17. [PMID: 23229060 DOI: 10.1007/s00425-012-1802-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/26/2012] [Indexed: 05/10/2023]
Abstract
In maize and other grasses there is a developmental gradient from the meristematic cells at the base of the stalk to the differentiated cells at the leaf tip. This gradient presents an opportunity to investigate changes in mitochondrial DNA (mtDNA) that accompany growth under light and dark conditions, as done previously for plastid DNA. Maize mtDNA was analyzed by DAPI-DNA staining of individual mitochondria, gel electrophoresis/blot hybridization, and real-time qPCR. Both the amount and integrity of the mtDNA were found to decline with development. There was a 20-fold decline in mtDNA copy number per cell from the embryo to the light-grown leaf blade. The amount of DNA per mitochondrial particle was greater in dark-grown leaf blade (24 copies, on average) than in the light (2 copies), with some mitochondria lacking any detectable DNA. Three factors that influence the demise of mtDNA during development are considered: (1) the decision to either repair or degrade mtDNA molecules that are damaged by the reactive oxygen species produced as byproducts of respiration; (2) the generation of ATP by photophosphorylation in chloroplasts, reducing the need for respiratory-competent mitochondria; and (3) the shift in mitochondrial function from energy-generating respiration to photorespiration during the transition from non-green to green tissue.
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Affiliation(s)
- Delene J Oldenburg
- Department of Biology, University of Washington, Seattle, WA 98195-5325, USA.
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Abstract
Plant mitochondrial genomes are notorious for their large and variable size, nonconserved open reading frames of unknown function, and high rates of rearrangement. Paradoxically, the mutation rates are very low. However, mutation rates can only be measured in sequences that can be aligned--a very small part of plant mitochondrial genomes. Comparison of the complete mitochondrial genome sequences of two ecotypes of Arabidopsis thaliana allows the alignment of noncoding as well as coding DNA and estimation of the mutation rates in both. A recent chimeric duplication is also analyzed. A hypothesis is proposed that the mechanisms of plant mitochondrial DNA repair account for these features and includes different mechanisms in transcribed and nontranscribed regions. Within genes, a bias toward gene conversion would keep measured mutation rates low, whereas in noncoding regions, break-induced replication (BIR) explains the expansion and rearrangements. Both processes are types of double-strand break repair, but enhanced second-strand capture in transcribed regions versus BIR in nontranscribed regions can explain the two seemingly contradictory features of plant mitochondrial genome evolution--the low mutation rates in genes and the striking expansions of noncoding sequences.
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Affiliation(s)
- Alan C Christensen
- School of Biological Sciences, E249 Beadle Center, University of Nebraska-Lincoln, USA.
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Sloan DB, Müller K, McCauley DE, Taylor DR, Štorchová H. Intraspecific variation in mitochondrial genome sequence, structure, and gene content in Silene vulgaris, an angiosperm with pervasive cytoplasmic male sterility. THE NEW PHYTOLOGIST 2012; 196:1228-1239. [PMID: 23009072 DOI: 10.1111/j.1469-8137.2012.04340.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 08/17/2012] [Indexed: 05/04/2023]
Abstract
In angiosperms, mitochondrial-encoded genes can cause cytoplasmic male sterility (CMS), resulting in the coexistence of female and hermaphroditic individuals (gynodioecy). We compared four complete mitochondrial genomes from the gynodioecious species Silene vulgaris and found unprecedented amounts of intraspecific diversity for plant mitochondrial DNA (mtDNA). Remarkably, only about half of overall sequence content is shared between any pair of genomes. The four mtDNAs range in size from 361 to 429 kb and differ in gene complement, with rpl5 and rps13 being intact in some genomes but absent or pseudogenized in others. The genomes exhibit essentially no conservation of synteny and are highly repetitive, with evidence of reciprocal recombination occurring even across short repeats (< 250 bp). Some mitochondrial genes exhibit atypically high degrees of nucleotide polymorphism, while others are invariant. The genomes also contain a variable number of small autonomously mapping chromosomes, which have only recently been identified in angiosperm mtDNA. Southern blot analysis of one of these chromosomes indicated a complex in vivo structure consisting of both monomeric circles and multimeric forms. We conclude that S. vulgaris harbors an unusually large degree of variation in mtDNA sequence and structure and discuss the extent to which this variation might be related to CMS.
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Affiliation(s)
- Daniel B Sloan
- Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA
| | - Karel Müller
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Lysolaje, 16502, Czech Republic
| | - David E McCauley
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, 37235, USA
| | - Douglas R Taylor
- Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA
| | - Helena Štorchová
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Lysolaje, 16502, Czech Republic
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Janicka S, Kühn K, Le Ret M, Bonnard G, Imbault P, Augustyniak H, Gualberto JM. A RAD52-like single-stranded DNA binding protein affects mitochondrial DNA repair by recombination. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 72:423-435. [PMID: 22762281 DOI: 10.1111/j.1365-313x.2012.05097.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The plant mitochondrial DNA-binding protein ODB1 was identified from a mitochondrial extract after DNA-affinity purification. ODB1 (organellar DNA-binding protein 1) co-purified with WHY2, a mitochondrial member of the WHIRLY family of plant-specific proteins involved in the repair of organellar DNA. The Arabidopsis thaliana ODB1 gene is identical to RAD52-1, which encodes a protein functioning in homologous recombination in the nucleus but additionally localizing to mitochondria. We confirmed the mitochondrial localization of ODB1 by in vitro and in vivo import assays, as well as by immunodetection on Arabidopsis subcellular fractions. In mitochondria, WHY2 and ODB1 were found in large nucleo-protein complexes. Both proteins co-immunoprecipitated in a DNA-dependent manner. In vitro assays confirmed DNA binding by ODB1 and showed that the protein has higher affinity for single-stranded than for double-stranded DNA. ODB1 showed no sequence specificity in vitro. In vivo, DNA co-immunoprecipitation indicated that ODB1 binds sequences throughout the mitochondrial genome. ODB1 promoted annealing of complementary DNA sequences, suggesting a RAD52-like function as a recombination mediator. Arabidopsis odb1 mutants were morphologically indistinguishable from the wild-type, but following DNA damage by genotoxic stress, they showed reduced mitochondrial homologous recombination activity. Under the same conditions, the odb1 mutants showed an increase in illegitimate repair bypasses generated by microhomology-mediated recombination. These observations identify ODB1 as a further component of homologous recombination-dependent DNA repair in plant mitochondria.
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Affiliation(s)
- Sabina Janicka
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France
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