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Edera AA, Howell KA, Nevill PG, Small I, Sanchez-Puerta MV. Evolution of cox2 introns in angiosperm mitochondria and efficient splicing of an elongated cox2i691 intron. Gene 2023; 869:147393. [PMID: 36966978 DOI: 10.1016/j.gene.2023.147393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/08/2023] [Accepted: 03/21/2023] [Indexed: 04/03/2023]
Abstract
In angiosperms, the mitochondrial cox2 gene harbors up to two introns, commonly referred to as cox2i373 and cox2i691. We studied the cox2 from 222 fully-sequenced mitogenomes from 30 angiosperm orders and analyzed the evolution of their introns. Unlike cox2i373, cox2i691 shows a distribution among plants that is shaped by frequent intron loss events driven by localized retroprocessing. In addition, cox2i691 exhibits sporadic elongations, frequently in domain IV of introns. Such elongations are poorly related to repeat content and two of them showed the presence of LINE transposons, suggesting that increasing intron size is very likely due to nuclear intracelular DNA transfer followed by incorporation into the mitochondrial DNA. Surprisingly, we found that cox2i691 is erroneously annotated as absent in 30 mitogenomes deposited in public databases. Although each of the cox2 introns is ∼1.5 kb in length, a cox2i691 of 4.2 kb has been reported in Acacia ligulata (Fabaceae). It is still unclear whether its unusual length is due to a trans-splicing arrangement or the loss of functionality of the interrupted cox2. Through analyzing short-read RNA sequencing of Acacia with a multi-step computational strategy, we found that the Acacia cox2 is functional and its long intron is spliced in cis in a very efficient manner despite its length.
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Affiliation(s)
- Alejandro A Edera
- Research Institute for Signals, Systems and Computational Intelligence, sinc(i), FICH-UNL, CONICET, Ciudad Universitaria UNL, 3000 Santa Fe, Argentina.
| | - Katharine A Howell
- Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Paul G Nevill
- Botanic Gardens and Parks Authority, Kings Park and Botanic Garden, Fraser Avenue, Kings Park, Western Australia, Australia; School of Plant Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Ian Small
- Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, Australia; Centre of Excellence in Computational Systems Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - M Virginia Sanchez-Puerta
- IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, 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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2
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Lee C, Ruhlman TA, Jansen RK. Rate accelerations in plastid and mitochondrial genomes of Cyperaceae occur in the same clades. Mol Phylogenet Evol 2023; 182:107760. [PMID: 36921696 DOI: 10.1016/j.ympev.2023.107760] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 01/28/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023]
Abstract
Cyperaceae, the second largest family in the monocot order Poales, comprises >5500 species and includes the genus Eleocharis with ∼ 250 species. A previous study of complete plastomes of two Eleocharis species documented extensive structural heteroplasmy, gene order changes, high frequency of dispersed repeats along with gene losses and duplications. To better understand the phylogenetic distribution of gene and intron content as well as rates and patterns of sequence evolution within and between mitochondrial and plastid genomes of Eleocharis and Cyperaceae, an additional 29 Eleocharis organelle genomes were sequenced and analyzed. Eleocharis experienced extensive gene loss in both genomes while loss of introns was mitochondria-specific. Eleocharis has higher rates of synonymous (dS) and nonsynonymous (dN) substitutions in the plastid and mitochondrion than most sampled angiosperms, and the pattern was distinct from other eudicot lineages with accelerated rates. Several clades showed higher dS and dN in mitochondrial genes than in plastid genes. Furthermore, nucleotide substitution rates of mitochondrial genes were significantly accelerated on the branch leading to Cyperaceae compared to most angiosperms. Mitochondrial genes of Cyperaceae exhibited dramatic loss of RNA editing sites and a negative correlation between RNA editing and dS values was detected among angiosperms. Mutagenic retroprocessing and dysfunction of DNA replication, repair and recombination genes are the most likely cause of striking rate accelerations and loss of edit sites and introns in Eleocharis and Cyperaceae organelle genomes.
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Affiliation(s)
- Chaehee Lee
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Plant Sciences, University of California, Davis, Davis, CA 95616, 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
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3
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Zhang MZ, Xu JP, Callac P, Chen MY, Wu Q, Wach M, Mata G, Zhao RL. Insight into the evolutionary and domesticated history of the most widely cultivated mushroom Agaricus bisporus via mitogenome sequences of 361 global strains. BMC Genomics 2023; 24:182. [PMID: 37020265 PMCID: PMC10077685 DOI: 10.1186/s12864-023-09257-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 03/20/2023] [Indexed: 04/07/2023] Open
Abstract
Agaricus bisporus is the most widely cultivated edible mushroom in the world with a only around three hundred years known history of cultivation. Therefore, it represents an ideal organism not only to investigate the natural evolutionary history but also the understanding on the evolution going back to the early era of domestication. In this study, we generated the mitochondrial genome sequences of 352 A. bisporus strains and 9 strains from 4 closely related species around the world. The population mitogenomic study revealed all A. bisporus strains can be divided into seven clades, and all domesticated cultivars present only in two of those clades. The molecular dating analysis showed this species origin in Europe on 4.6 Ma and we proposed the main dispersal routes. The detailed mitogenome structure studies showed that the insertion of the plasmid-derived dpo gene caused a long fragment (MIR) inversion, and the distributions of the fragments of dpo gene were strictly in correspondence with these seven clades. Our studies also showed A. bisporus population contains 30 intron distribution patterns (IDPs), while all cultivars contain only two IDPs, which clearly exhibit intron loss compared to the others. Either the loss occurred before or after domestication, that could suggest that the change facilitates their adaptation to the cultivated environment.
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Affiliation(s)
- Ming-Zhe Zhang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, No3 1St Beichen West Road, Beijing, 100101, Chaoyang District, China
- College of Life Sciences, University of Chinese Academy of Sciences, Huairou District, Beijing, 101408, China
| | - Jian-Ping Xu
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | | | - Mei-Yuan Chen
- Edible Fungi Institute of Fujian Academy of Agricultural Sciences, Fuzhou, 350014, China
| | - Qi Wu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, No3 1St Beichen West Road, Beijing, 100101, Chaoyang District, China
- College of Life Sciences, University of Chinese Academy of Sciences, Huairou District, Beijing, 101408, China
| | - Mark Wach
- Sylvan BioSciences, Kittanning, PA, 16201, USA
| | - Gerardo Mata
- Instituto de Ecología A.C. Carretera Antigua a Coatepec, 351, El Haya, 91073, Veracruz, CPXalapa, Mexico
| | - Rui-Lin Zhao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, No3 1St Beichen West Road, Beijing, 100101, Chaoyang District, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Huairou District, Beijing, 101408, China.
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4
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Wu CS, Chen CI, Chaw SM. Plastid phylogenomics and plastome evolution in the morning glory family (Convolvulaceae). FRONTIERS IN PLANT SCIENCE 2022; 13:1061174. [PMID: 36605953 PMCID: PMC9808526 DOI: 10.3389/fpls.2022.1061174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Convolvulaceae, the morning glories or bindweeds, is a large family containing species of economic value, including crops, traditional medicines, ornamentals, and vegetables. However, not only are the phylogenetic relationships within this group still debated at the intertribal and intergeneric levels, but also plastid genome (plastome) complexity within Convolvulaceae is not well surveyed. We gathered 78 plastomes representing 17 genera across nine of the 12 Convolvulaceae tribes. Our plastid phylogenomic trees confirm the monophyly of Convolvulaceae, place the genus Jacquemontia within the subfamily Dicranostyloideae, and suggest that the tribe Merremieae is paraphyletic. In contrast, positions of the two genera Cuscuta and Erycibe are uncertain as the bootstrap support of the branches leading to them is moderate to weak. We show that nucleotide substitution rates are extremely variable among Convolvulaceae taxa and likely responsible for the topological uncertainty. Numerous plastomic rearrangements are detected in Convolvulaceae, including inversions, duplications, contraction and expansion of inverted repeats (IRs), and losses of genes and introns. Moreover, integrated foreign DNA of mitochondrial origin was found in the Jacquemontia plastome, adding a rare example of gene transfer from mitochondria to plastids in angiosperms. In the IR of Dichondra, we discovered an extra copy of rpl16 containing a direct repeat of ca. 200 bp long. This repeat was experimentally demonstrated to trigger effective homologous recombination, resulting in the coexistence of intron-containing and -lacking rpl16 duplicates. Therefore, we propose a hypothetical model to interpret intron loss accompanied by invasion of direct repeats at appropriate positions. Our model complements the intron loss model driven by retroprocessing when genes have lost introns but contain abundant RNA editing sites adjacent to former splicing sites.
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Affiliation(s)
- Chung-Shien Wu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Chung-I. Chen
- Department of Forestry, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shu-Miaw Chaw
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
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Klimpert NJ, Mayer JLS, Sarzi DS, Prosdocimi F, Pinheiro F, Graham SW. Phylogenomics and plastome evolution of a Brazilian mycoheterotrophic orchid, Pogoniopsis schenckii. AMERICAN JOURNAL OF BOTANY 2022; 109:2030-2050. [PMID: 36254561 DOI: 10.1002/ajb2.16084] [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: 04/14/2022] [Revised: 09/23/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
PREMISE Pogoniopsis likely represents an independent photosynthesis loss in orchids. We use phylogenomic data to better identify the phylogenetic placement of this fully mycoheterotrophic taxon, and investigate its molecular evolution. METHODS We performed likelihood analysis of plastid and mitochondrial phylogenomic data to localize the position of Pogoniopsis schenckii in orchid phylogeny, and investigated the evolution of its plastid genome. RESULTS All analyses place Pogoniopsis in subfamily Epidendroideae, with strongest support from mitochondrial data, which also place it near tribe Sobralieae with moderately strong support. Extreme rate elevation in Pogoniopsis plastid genes broadly depresses branch support; in contrast, mitochondrial genes are only mildly rate elevated and display very modest and localized reductions in bootstrap support. Despite considerable genome reduction, including loss of photosynthesis genes and multiple translation apparatus genes, gene order in Pogoniopsis plastomes is identical to related autotrophs, apart from moderately shifted inverted repeat (IR) boundaries. All cis-spliced introns have been lost in retained genes. Two plastid genes (accD, rpl2) show significant strengthening of purifying selection. A retained plastid tRNA gene (trnE-UUC) of Pogoniopsis lacks an anticodon; we predict that it no longer functions in translation but retains a secondary role in heme biosynthesis. CONCLUSIONS Slowly evolving mitochondrial genes clarify the placement of Pogoniopsis in orchid phylogeny, a strong contrast with analysis of rate-elevated plastome data. We documented the effects of the novel loss of photosynthesis: for example, despite massive gene loss, its plastome is fully colinear with other orchids, and it displays only moderate shifts in selective pressure in retained genes.
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Affiliation(s)
- Nathaniel J Klimpert
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Juliana Lischka Sampaio Mayer
- Departamento de Biologia Vegetal, Universidade Estadual de Campinas, 255 Rua Monteiro Lobato, Campinas, São Paulo, 13.083-862, Brazil
| | - Deise Schroder Sarzi
- Laboratório de Genômica e Biodiversidade, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal Do Rio de Janeiro, UFRJ/CCS/Bloco B33, Rio de Janeiro, RJ, 21.941-902, Brazil
| | - Francisco Prosdocimi
- Laboratório de Genômica e Biodiversidade, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal Do Rio de Janeiro, UFRJ/CCS/Bloco B33, Rio de Janeiro, RJ, 21.941-902, Brazil
| | - Fábio Pinheiro
- Departamento de Biologia Vegetal, Universidade Estadual de Campinas, 255 Rua Monteiro Lobato, Campinas, São Paulo, 13.083-862, Brazil
| | - Sean W Graham
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
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Mukhopadhyay J, Hausner G. Organellar Introns in Fungi, Algae, and Plants. Cells 2021; 10:cells10082001. [PMID: 34440770 PMCID: PMC8393795 DOI: 10.3390/cells10082001] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/31/2021] [Accepted: 08/05/2021] [Indexed: 12/16/2022] Open
Abstract
Introns are ubiquitous in eukaryotic genomes and have long been considered as ‘junk RNA’ but the huge energy expenditure in their transcription, removal, and degradation indicate that they may have functional significance and can offer evolutionary advantages. In fungi, plants and algae introns make a significant contribution to the size of the organellar genomes. Organellar introns are classified as catalytic self-splicing introns that can be categorized as either Group I or Group II introns. There are some biases, with Group I introns being more frequently encountered in fungal mitochondrial genomes, whereas among plants Group II introns dominate within the mitochondrial and chloroplast genomes. Organellar introns can encode a variety of proteins, such as maturases, homing endonucleases, reverse transcriptases, and, in some cases, ribosomal proteins, along with other novel open reading frames. Although organellar introns are viewed to be ribozymes, they do interact with various intron- or nuclear genome-encoded protein factors that assist in the intron RNA to fold into competent splicing structures, or facilitate the turn-over of intron RNAs to prevent reverse splicing. Organellar introns are also known to be involved in non-canonical splicing, such as backsplicing and trans-splicing which can result in novel splicing products or, in some instances, compensate for the fragmentation of genes by recombination events. In organellar genomes, Group I and II introns may exist in nested intronic arrangements, such as introns within introns, referred to as twintrons, where splicing of the external intron may be dependent on splicing of the internal intron. These nested or complex introns, with two or three-component intron modules, are being explored as platforms for alternative splicing and their possible function as molecular switches for modulating gene expression which could be potentially applied towards heterologous gene expression. This review explores recent findings on organellar Group I and II introns, focusing on splicing and mobility mechanisms aided by associated intron/nuclear encoded proteins and their potential roles in organellar gene expression and cross talk between nuclear and organellar genomes. Potential application for these types of elements in biotechnology are also discussed.
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MESH Headings
- Evolution, Molecular
- Gene Expression Regulation, Fungal
- Gene Expression Regulation, Plant
- Genome, Fungal
- Genome, Plant
- Introns
- Organelles/genetics
- Organelles/metabolism
- RNA Splicing
- RNA Stability
- RNA, Algal/genetics
- RNA, Algal/metabolism
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Transcription, Genetic
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7
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Abstract
Computers are able to systematically exploit RNA-seq data allowing us to efficiently detect RNA editing sites in a genome-wide scale. This chapter introduces a very flexible computational framework for detecting RNA editing sites in plant organelles. This framework comprises three major steps: RNA-seq data processing, RNA read alignment, and RNA editing site detection. Each step is discussed in sufficient detail to be implemented by the reader. As a study case, the framework will be used with publicly available sequencing data to detect C-to-U RNA editing sites in the coding sequences of the mitochondrial genome of Nicotiana tabacum.
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Affiliation(s)
- Alejandro A Edera
- Facultad de Ciencias Agrarias, IBAM, Universidad Nacional de Cuyo, CONICET, Almirante Brown, Argentina.
| | - M Virginia Sanchez-Puerta
- Facultad de Ciencias Agrarias, IBAM, Universidad Nacional de Cuyo, CONICET, Almirante Brown, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
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8
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Choi K, Weng ML, Ruhlman TA, Jansen RK. Extensive variation in nucleotide substitution rate and gene/intron loss in mitochondrial genomes of Pelargonium. Mol Phylogenet Evol 2020; 155:106986. [PMID: 33059063 DOI: 10.1016/j.ympev.2020.106986] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 07/16/2020] [Accepted: 10/07/2020] [Indexed: 12/30/2022]
Abstract
Geraniaceae organelle genomes have been shown to exhibit several highly unusual features compared to most other photosynthetic angiosperms. This includes massively rearranged plastomes with considerable size variation, extensive gene and intron loss, accelerated rates of nucleotide substitutions in both mitogenomes and plastomes, and biparental inheritance and cytonuclear incompatibility of the plastome. Most previous studies have focused on plastome evolution with mitogenome comparisons limited to only a few taxa or genes. In this study, mitogenomes and transcriptomes were examined for 27 species of Geraniales, including 13 species of Pelargonium. Extensive gene and intron losses were detected across the Geraniales with Pelargonium representing the most gene depauperate lineage in the family. Plotting these events on the Geraniaceae phylogenetic tree showed that gene losses occurred multiple times, whereas intron losses more closely reflected the relationships among taxa. In addition, P. australe acquired an intron by horizontal transfer. Comparisons of nucleotide substitution rates in Pelargonium showed that synonymous changes in nuclear genes were much lower than in mitochondrial genes. This is in contrast to the previously published studies that indicated that nuclear genes have 16 fold higher rates than mitochondrial genes across angiosperms. Elevated synonymous substitutions occurred for each mitochondrial gene in Pelargonium with the highest values 783 and 324 times higher than outgroups and other Geraniaceae, respectively. Pelargonium is one of four unrelated genera of angiosperms (Ajuga, Plantago and Silene) that have experienced highly accelerated nucleotide substitutions in mitogenomes. It is distinct from most angiosperms in also having elevated substitution rates in plastid genes but the cause of rate accelerations in Pelargonium plastomes and mitogenomes may be different.
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Affiliation(s)
- KyoungSu Choi
- Department of Integrative Biology, University of Texas, Austin, TX 78712, USA
| | - Mao-Lun Weng
- Department of Biology, Westfield State University, Westfield, MA, USA
| | - Tracey A Ruhlman
- Department of Integrative Biology, University of Texas, Austin, TX 78712, USA
| | - Robert K Jansen
- Department of Integrative Biology, University of Texas, Austin, TX 78712, USA; Center for Excellence for Bionanoscience Research, King Abdulaziz University (KAU), Jeddah 21589, Saudi Arabia.
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9
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Kaeser G, Chun J. Brain cell somatic gene recombination and its phylogenetic foundations. J Biol Chem 2020; 295:12786-12795. [PMID: 32699111 PMCID: PMC7476723 DOI: 10.1074/jbc.rev120.009192] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 07/22/2020] [Indexed: 12/19/2022] Open
Abstract
A new form of somatic gene recombination (SGR) has been identified in the human brain that affects the Alzheimer's disease gene, amyloid precursor protein (APP). SGR occurs when a gene sequence is cut and recombined within a single cell's genomic DNA, generally independent of DNA replication and the cell cycle. The newly identified brain SGR produces genomic complementary DNAs (gencDNAs) lacking introns, which integrate into locations distinct from germline loci. This brief review will present an overview of likely related recombination mechanisms and genomic cDNA-like sequences that implicate evolutionary origins for brain SGR. Similarities and differences exist between brain SGR and VDJ recombination in the immune system, the first identified SGR form that now has a well-defined enzymatic machinery. Both require gene transcription, but brain SGR uses an RNA intermediate and reverse transcriptase (RT) activity, which are characteristics shared with endogenous retrotransposons. The identified gencDNAs have similarities to other cDNA-like sequences existing throughout phylogeny, including intron-less genes and inactive germline processed pseudogenes, with likely overlapping biosynthetic processes. gencDNAs arise somatically in an individual to produce multiple copies; can be functional; appear most frequently within postmitotic cells; have diverse sequences; change with age; and can change with disease state. Normally occurring brain SGR may represent a mechanism for gene optimization and long-term cellular memory, whereas its dysregulation could underlie multiple brain disorders and, potentially, other diseases like cancer. The involvement of RT activity implicates already Food and Drug Administration-approved RT inhibitors as possible near-term interventions for managing SGR-associated diseases and suggest next-generation therapeutics targeting SGR elements.
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Affiliation(s)
- Gwendolyn Kaeser
- Degenerative Disease Program at the Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jerold Chun
- Degenerative Disease Program at the Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
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10
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Mower JP. Variation in protein gene and intron content among land plant mitogenomes. Mitochondrion 2020; 53:203-213. [PMID: 32535166 DOI: 10.1016/j.mito.2020.06.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 05/24/2020] [Accepted: 06/08/2020] [Indexed: 12/20/2022]
Abstract
The functional content of the mitochondrial genome (mitogenome) is highly diverse across eukaryotes. Among land plants, our understanding of the variation in mitochondrial gene and intron content is improving from concerted efforts to densely sample mitogenomes from diverse land plants. Here I review the current state of knowledge regarding the diversity in content of protein genes and introns in the mitogenomes of all major land plant lineages. Mitochondrial protein gene content is largely conserved among mosses and liverworts, but it varies substantially among and within other land plant lineages due to convergent losses of genes encoding ribosomal proteins and, to a lesser extent, genes for proteins involved in cytochrome c maturation and oxidative phosphorylation. Mitochondrial intron content is fairly stable within each major land plant lineage, but highly variable among lineages, resulting from occasional gains and many convergent losses over time. Trans-splicing has evolved dozens of times in various vascular plant lineages, particularly those with relatively higher rates of mitogenomic rearrangement. Across eukaryotes, mitochondrial protein gene and intron content has been shaped massive convergent evolution.
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Affiliation(s)
- Jeffrey P Mower
- Center for Plant Science Innovation and Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE.
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11
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Logacheva MD, Schelkunov MI, Fesenko AN, Kasianov AS, Penin AA. Mitochondrial Genome of Fagopyrum esculentum and the Genetic Diversity of Extranuclear Genomes in Buckwheat. PLANTS (BASEL, SWITZERLAND) 2020; 9:E618. [PMID: 32408719 PMCID: PMC7285332 DOI: 10.3390/plants9050618] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/08/2020] [Accepted: 05/09/2020] [Indexed: 12/27/2022]
Abstract
Fagopyrum esculentum (common buckwheat) is an important agricultural non-cereal grain plant. Despite extensive genetic studies, the information on its mitochondrial genome is still lacking. Using long reads generated by single-molecule real-time technology coupled with circular consensus sequencing (CCS) protocol, we assembled the buckwheat mitochondrial genome and detected that its prevalent form consists of 10 circular chromosomes with a total length of 404 Kb. In order to confirm the presence of a multipartite structure, we developed a new targeted assembly tool capable of processing long reads. The mitogenome contains all genes typical for plant mitochondrial genomes and long inserts of plastid origin (~6.4% of the total mitogenome length). Using this new information, we characterized the genetic diversity of mitochondrial and plastid genomes in 11 buckwheat cultivars compared with the ancestral subspecies, F. esculentum ssp. ancestrale. We found it to be surprisingly low within cultivars: Only three to six variations in the mitogenome and one to two in the plastid genome. In contrast, the divergence with F. esculentum ssp. ancestrale is much higher: 220 positions differ in the mitochondrial genome and 159 in the plastid genome. The SNPs in the plastid genome are enriched in non-synonymous substitutions, in particular in the genes involved in photosynthesis: psbA, psbC, and psbH. This presumably reflects the selection for the increased photosynthesis efficiency as a part of the buckwheat breeding program.
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Affiliation(s)
- Maria D. Logacheva
- Institute for Information Transmission Problems of the Russian Academy of Sciences, 127051 Moscow, Russia; (M.I.S.); (A.S.K.); (A.A.P.)
- Skolkovo Institute of Science and Technology, 143026 Moscow, Russia
| | - Mikhail I. Schelkunov
- Institute for Information Transmission Problems of the Russian Academy of Sciences, 127051 Moscow, Russia; (M.I.S.); (A.S.K.); (A.A.P.)
- Skolkovo Institute of Science and Technology, 143026 Moscow, Russia
| | - Aleksey N. Fesenko
- Federal Scientific Center of Legumes and Groat Crops, 302502 Orel, Russia;
| | - Artem S. Kasianov
- Institute for Information Transmission Problems of the Russian Academy of Sciences, 127051 Moscow, Russia; (M.I.S.); (A.S.K.); (A.A.P.)
| | - Aleksey A. Penin
- Institute for Information Transmission Problems of the Russian Academy of Sciences, 127051 Moscow, Russia; (M.I.S.); (A.S.K.); (A.A.P.)
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12
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Kan SL, Shen TT, Gong P, Ran JH, Wang XQ. The complete mitochondrial genome of Taxus cuspidata (Taxaceae): eight protein-coding genes have transferred to the nuclear genome. BMC Evol Biol 2020; 20:10. [PMID: 31959109 PMCID: PMC6971862 DOI: 10.1186/s12862-020-1582-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/13/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Gymnosperms represent five of the six lineages of seed plants. However, most sequenced plant mitochondrial genomes (mitogenomes) have been generated for angiosperms, whereas mitogenomic sequences have been generated for only six gymnosperms. In particular, complete mitogenomes are available for all major seed plant lineages except Conifer II (non-Pinaceae conifers or Cupressophyta), an important lineage including six families, which impedes a comprehensive understanding of the mitogenomic diversity and evolution in gymnosperms. RESULTS Here, we report the complete mitogenome of Taxus cuspidata in Conifer II. In comparison with previously released gymnosperm mitogenomes, we found that the mitogenomes of Taxus and Welwitschia have lost many genes individually, whereas all genes were identified in the mitogenomes of Cycas, Ginkgo and Pinaceae. Multiple tRNA genes and introns also have been lost in some lineages of gymnosperms, similar to the pattern observed in angiosperms. In general, gene clusters could be less conserved in gymnosperms than in angiosperms. Moreover, fewer RNA editing sites were identified in the Taxus and Welwitschia mitogenomes than in other mitogenomes, which could be correlated with fewer introns and frequent gene losses in these two species. CONCLUSIONS We have sequenced the Taxus cuspidata mitogenome, and compared it with mitogenomes from the other four gymnosperm lineages. The results revealed the diversity in size, structure, gene and intron contents, foreign sequences, and mutation rates of gymnosperm mitogenomes, which are different from angiosperm mitogenomes.
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Affiliation(s)
- Sheng-Long Kan
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ting-Ting Shen
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Ping Gong
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Jin-Hua Ran
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Xiao-Quan Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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13
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Dong S, Zhao C, Zhang S, Zhang L, Wu H, Liu H, Zhu R, Jia Y, Goffinet B, Liu Y. Mitochondrial genomes of the early land plant lineage liverworts (Marchantiophyta): conserved genome structure, and ongoing low frequency recombination. BMC Genomics 2019; 20:953. [PMID: 31818248 PMCID: PMC6902596 DOI: 10.1186/s12864-019-6365-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/02/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND In contrast to the highly labile mitochondrial (mt) genomes of vascular plants, the architecture and composition of mt genomes within the main lineages of bryophytes appear stable and invariant. The available mt genomes of 18 liverwort accessions representing nine genera and five orders are syntenous except for Gymnomitrion concinnatum whose genome is characterized by two rearrangements. Here, we expanded the number of assembled liverwort mt genomes to 47, broadening the sampling to 31 genera and 10 orders spanning much of the phylogenetic breadth of liverworts to further test whether the evolution of the liverwort mitogenome is overall static. RESULTS Liverwort mt genomes range in size from 147 Kb in Jungermanniales (clade B) to 185 Kb in Marchantiopsida, mainly due to the size variation of intergenic spacers and number of introns. All newly assembled liverwort mt genomes hold a conserved set of genes, but vary considerably in their intron content. The loss of introns in liverwort mt genomes might be explained by localized retroprocessing events. Liverwort mt genomes are strictly syntenous in genome structure with no structural variant detected in our newly assembled mt genomes. However, by screening the paired-end reads, we do find rare cases of recombination, which means multiple concurrent genome structures may exist in the vegetative tissues of liverworts. Our phylogenetic analyses of the nuclear encoded double stand break repair protein families revealed liverwort-specific subfamilies expansions. CONCLUSIONS The low repeat recombination level, selection, along with the intensified nuclear surveillance, might together shape the structural evolution of liverwort mt genomes.
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Affiliation(s)
- Shanshan Dong
- Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Sciences, Shenzhen, 518004 China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Chaoxian Zhao
- Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Sciences, Shenzhen, 518004 China
- Department of Biology, School of Life Sciences, East China Normal University, Shanghai, 200241 China
| | - Shouzhou Zhang
- Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Sciences, Shenzhen, 518004 China
| | - Li Zhang
- Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Sciences, Shenzhen, 518004 China
| | - Hong Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Huan Liu
- BGI-Shenzhen, Shenzhen, 518083 China
| | - Ruiliang Zhu
- Department of Biology, School of Life Sciences, East China Normal University, Shanghai, 200241 China
| | - Yu Jia
- State Key Laboratory of Systematic and Evolutionary Botany, Chinese Academy of Sciences, Institute of Botany, Beijing, 100093 China
| | - Bernard Goffinet
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043 USA
| | - Yang Liu
- Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Sciences, Shenzhen, 518004 China
- BGI-Shenzhen, Shenzhen, 518083 China
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14
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Petersen G, Darby H, Lam VKY, Pedersen HÆ, Merckx VSFT, Zervas A, Seberg O, Graham SW. Mycoheterotrophic Epirixanthes (Polygalaceae) has a typical angiosperm mitogenome but unorthodox plastid genomes. ANNALS OF BOTANY 2019; 124:791-807. [PMID: 31346602 PMCID: PMC6868387 DOI: 10.1093/aob/mcz114] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/24/2019] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS Fully mycoheterotrophic plants derive carbon and other nutrients from root-associated fungi and have lost the ability to photosynthesize. While mycoheterotroph plastomes are often degraded compared with green plants, the effect of this unusual symbiosis on mitochondrial genome evolution is unknown. By providing the first complete organelle genome data from Polygalaceae, one of only three eudicot families that developed mycoheterotrophy, we explore how both organellar genomes evolved after loss of photosynthesis. METHODS We sequenced and assembled four complete plastid genomes and a mitochondrial genome from species of Polygalaceae, focusing on non-photosynthetic Epirixanthes. We compared these genomes with those of other mycoheterotroph and parasitic plant lineages, and assessed whether organelle genes in Epirixanthes experienced relaxed or intensified selection compared with autotrophic relatives. KEY RESULTS Plastomes of two species of Epirixanthes have become substantially degraded compared with that of autotrophic Polygala. Although the lack of photosynthesis is presumably homologous in the genus, the surveyed Epirixanthes species have marked differences in terms of plastome size, structural rearrangements, gene content and substitution rates. Remarkably, both apparently replaced a canonical plastid inverted repeat with large directly repeated sequences. The mitogenome of E. elongata incorporated a considerable number of fossilized plastid genes, by intracellular transfer from an ancestor with a less degraded plastome. Both plastid and mitochondrial genes in E. elongata have increased substitution rates, but the plastid genes of E. pallida do not. Despite this, both species have similar selection patterns operating on plastid housekeeping genes. CONCLUSIONS Plastome evolution largely fits with patterns of gene degradation seen in other heterotrophic plants, but includes highly unusual directly duplicated regions. The causes of rate elevation in the sequenced Epirixanthes mitogenome and of rate differences in plastomes of related mycoheterotrophic species are not currently understood.
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Affiliation(s)
- G Petersen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
- For correspondence. E-mail:
| | - H Darby
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- UBC Botanical Garden & Centre for Plant Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - V K Y Lam
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- UBC Botanical Garden & Centre for Plant Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - H Æ Pedersen
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | | | - A Zervas
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
- Department of Environmental Science, Aarhus University, Denmark
| | - O Seberg
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - S W Graham
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- UBC Botanical Garden & Centre for Plant Research, University of British Columbia, Vancouver, British Columbia, Canada
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15
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Myszczyński K, Ślipiko M, Sawicki J. Potential of Transcript Editing Across Mitogenomes of Early Land Plants Shows Novel and Familiar Trends. Int J Mol Sci 2019; 20:E2963. [PMID: 31216623 PMCID: PMC6627324 DOI: 10.3390/ijms20122963] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 06/15/2019] [Accepted: 06/17/2019] [Indexed: 01/04/2023] Open
Abstract
RNA editing alters the identity of nucleotides in an RNA sequence so that the mature transcript differs from the template defined in the genome. This process has been observed in chloroplasts and mitochondria of both seed and early land plants. However, the frequency of RNA editing in plant mitochondria ranges from zero to thousands of editing sites. To date, analyses of RNA editing in mitochondria of early land plants have been conducted on a small number of genes or mitochondrial genomes of a single species. This study provides an overview of the mitogenomic RNA editing potential of the main lineages of these two groups of early land plants by predicting the RNA editing sites of 33 mitochondrial genes of 37 species of liverworts and mosses. For the purpose of the research, we newly assembled seven mitochondrial genomes of liverworts. The total number of liverwort genera with known complete mitogenome sequences has doubled and, as a result, the available complete mitogenome sequences now span almost all orders of liverworts. The RNA editing site predictions revealed that C-to-U RNA editing in liverworts and mosses is group-specific. This is especially evident in the case of liverwort lineages. The average level of C-to-U RNA editing appears to be over three times higher in liverworts than in mosses, while the C-to-U editing frequency of the majority of genes seems to be consistent for each gene across bryophytes.
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Affiliation(s)
- Kamil Myszczyński
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Plac Łódzki 1, 10-727 Olsztyn, Poland.
| | - Monika Ślipiko
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Plac Łódzki 1, 10-727 Olsztyn, Poland.
| | - Jakub Sawicki
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Plac Łódzki 1, 10-727 Olsztyn, Poland.
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16
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Mower JP, Ma P, Grewe F, Taylor A, Michael TP, VanBuren R, Qiu Y. Lycophyte plastid genomics: extreme variation in GC, gene and intron content and multiple inversions between a direct and inverted orientation of the rRNA repeat. THE NEW PHYTOLOGIST 2019; 222:1061-1075. [PMID: 30556907 PMCID: PMC6590440 DOI: 10.1111/nph.15650] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 12/10/2018] [Indexed: 05/02/2023]
Abstract
Lycophytes are a key group for understanding vascular plant evolution. Lycophyte plastomes are highly distinct, indicating a dynamic evolutionary history, but detailed evaluation is hindered by the limited availability of sequences. Eight diverse plastomes were sequenced to assess variation in structure and functional content across lycophytes. Lycopodiaceae plastomes have remained largely unchanged compared with the common ancestor of land plants, whereas plastome evolution in Isoetes and especially Selaginella is highly dynamic. Selaginella plastomes have the highest GC content and fewest genes and introns of any photosynthetic land plant. Uniquely, the canonical inverted repeat was converted into a direct repeat (DR) via large-scale inversion in some Selaginella species. Ancestral reconstruction identified additional putative transitions between an inverted and DR orientation in Selaginella and Isoetes plastomes. A DR orientation does not disrupt the activity of copy-dependent repair to suppress substitution rates within repeats. Lycophyte plastomes include the most archaic examples among vascular plants and the most reconfigured among land plants. These evolutionary trends correlate with the mitochondrial genome, suggesting shared underlying mechanisms. Copy-dependent repair for DR-localized genes indicates that recombination and gene conversion are not inhibited by the DR orientation. Gene relocation in lycophyte plastomes occurs via overlapping inversions rather than transposase/recombinase-mediated processes.
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Affiliation(s)
- Jeffrey P. Mower
- Center for Plant Science InnovationUniversity of NebraskaLincolnNE68588USA
- Department of Agronomy and HorticultureUniversity of NebraskaLincolnNE68583USA
| | - Peng‐Fei Ma
- Center for Plant Science InnovationUniversity of NebraskaLincolnNE68588USA
- Germplasm Bank of Wild SpeciesKunming Institute of BotanyChinese Academy of SciencesKunmingYunnan650201China
| | - Felix Grewe
- Grainger Bioinformatics Center, Science and EducationField Museum of Natural HistoryChicagoIL60605USA
| | - Alex Taylor
- Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMI48109USA
| | | | - Robert VanBuren
- Department of HorticultureMichigan State UniversityEast LansingMI48824USA
| | - Yin‐Long Qiu
- Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMI48109USA
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17
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Tsujimura M, Kaneko T, Sakamoto T, Kimura S, Shigyo M, Yamagishi H, Terachi T. Multichromosomal structure of the onion mitochondrial genome and a transcript analysis. Mitochondrion 2018; 46:179-186. [PMID: 30006008 DOI: 10.1016/j.mito.2018.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/30/2018] [Indexed: 11/29/2022]
Abstract
The structures of plant mitochondrial genomes are more complex than those of animals. One of the reasons for this is that plant mitochondrial genomes typically have many long and short repeated sequences and intra- and intermolecular recombination may create various DNA molecules in this organelle. Recombination may sometimes create a novel gene that causes cytoplasmic male sterility (CMS). The onion has several cytoplasm types, with some causing CMS while others do not. The complete mitochondrial genome sequence of the onion was reported for an inbred line with CMS-S cytoplasm; however, the number of differences between onion strains remains unclear, and studies on purified mitochondrial DNA (mtDNA) have not yet been performed. Furthermore, analyses of transcripts in the mitochondrial genome have not been conducted. In the present study, we examined the mitochondrial genome of the onion variety "Momiji-3" (Allium cepa L.) possessing CMS-S-type cytoplasm using next-generation sequencing (NGS). The "Momiji-3" mitochondrial genome mainly exists as three circles as a result of recombination through repeated sequences and we herein succeeded for the first time in visualizing its structure using pulsed field gel electrophoresis (PFGE). The ability to clarify the structure of the mitochondrial genome is rare in plant mitochondria; therefore, "Momiji-3" represents a good example for elucidating complex plant mitochondrial genomes. We also mapped transcript data to the mitochondrial genome in order to identify the RNA-editing positions in all gene-coding regions and estimate the expression levels of genes. We identified 635 editing positions in gene-coding regions. Start and stop codons were created by RNA editing in six genes (nad1, nad4L, atp6, atp9, ccmFC, and orf725). The transcript amounts of novel open reading frames (ORFs) were all markedly lower than those of functional genes. These results suggest that a new functional gene was not present in the mitochondrial genome of "Momiji-3", and that the candidate gene for CMS is orf725, as previously reported.
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Affiliation(s)
- Mai Tsujimura
- Plant Organelle Genome Research Center, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Takakazu Kaneko
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Tomoaki Sakamoto
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Seisuke Kimura
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan; Center for Ecological Evolutionary Developmental Biology, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Masayoshi Shigyo
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Hiroshi Yamagishi
- Plant Organelle Genome Research Center, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan; Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Toru Terachi
- Plant Organelle Genome Research Center, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan; Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan.
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18
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Edera AA, Gandini CL, Sanchez-Puerta MV. Towards a comprehensive picture of C-to-U RNA editing sites in angiosperm mitochondria. PLANT MOLECULAR BIOLOGY 2018; 97:215-231. [PMID: 29761268 DOI: 10.1007/s11103-018-0734-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
Our understanding of the dynamic and evolution of RNA editing in angiosperms is in part limited by the few editing sites identified to date. This study identified 10,217 editing sites from 17 diverse angiosperms. Our analyses confirmed the universality of certain features of RNA editing, and offer new evidence behind the loss of editing sites in angiosperms. RNA editing is a post-transcriptional process that substitutes cytidines (C) for uridines (U) in organellar transcripts of angiosperms. These substitutions mostly take place in mitochondrial messenger RNAs at specific positions called editing sites. By means of publicly available RNA-seq data, this study identified 10,217 editing sites in mitochondrial protein-coding genes of 17 diverse angiosperms. Even though other types of mismatches were also identified, we did not find evidence of non-canonical editing processes. The results showed an uneven distribution of editing sites among species, genes, and codon positions. The analyses revealed that editing sites were conserved across angiosperms but there were some species-specific sites. Non-synonymous editing sites were particularly highly conserved (~ 80%) across the plant species and were efficiently edited (80% editing extent). In contrast, editing sites at third codon positions were poorly conserved (~ 30%) and only partially edited (~ 40% editing extent). We found that the loss of editing sites along angiosperm evolution is mainly occurring by replacing editing sites with thymidines, instead of a degradation of the editing recognition motif around editing sites. Consecutive and highly conserved editing sites had been replaced by thymidines as result of retroprocessing, by which edited transcripts are reverse transcribed to cDNA and then integrated into the genome by homologous recombination. This phenomenon was more pronounced in eudicots, and in the gene cox1. These results suggest that retroprocessing is a widespread driving force underlying the loss of editing sites in angiosperm mitochondria.
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Affiliation(s)
- Alejandro A Edera
- IBAM, Facultad de Ciencias Agrarias, CONICET, Universidad Nacional de Cuyo, M5528AHB, Chacras de Coria, Argentina.
| | - Carolina L Gandini
- IBAM, Facultad de Ciencias Agrarias, CONICET, Universidad Nacional de Cuyo, M5528AHB, Chacras de Coria, Argentina
| | - M Virginia Sanchez-Puerta
- IBAM, Facultad de Ciencias Agrarias, CONICET, Universidad Nacional de Cuyo, M5528AHB, Chacras de Coria, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
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19
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Comparative Analysis of Four Calypogeia Species Revealed Unexpected Change in Evolutionarily-Stable Liverwort Mitogenomes. Genes (Basel) 2017; 8:genes8120395. [PMID: 29257096 PMCID: PMC5748713 DOI: 10.3390/genes8120395] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 11/17/2022] Open
Abstract
Liverwort mitogenomes are considered to be evolutionarily stable. A comparative analysis of four Calypogeia species revealed differences compared to previously sequenced liverwort mitogenomes. Such differences involve unexpected structural changes in the two genes, cox1 and atp1, which have lost three and two introns, respectively. The group I introns in the cox1 gene are proposed to have been lost by two-step localized retroprocessing, whereas one-step retroprocessing could be responsible for the disappearance of the group II introns in the atp1 gene. These cases represent the first identified losses of introns in mitogenomes of leafy liverworts (Jungermanniopsida) contrasting the stability of mitochondrial gene order with certain changes in the gene content and intron set in liverworts.
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20
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Wu Z, Sloan DB, Brown CW, Rosenblueth M, Palmer JD, Ong HC. Mitochondrial Retroprocessing Promoted Functional Transfers of rpl5 to the Nucleus in Grasses. Mol Biol Evol 2017; 34:2340-2354. [PMID: 28541477 PMCID: PMC5850859 DOI: 10.1093/molbev/msx170] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Functional gene transfers from the mitochondrion to the nucleus are ongoing in angiosperms and have occurred repeatedly for all 15 ribosomal protein genes, but it is not clear why some of these genes are transferred more often than others nor what the balance is between DNA- and RNA-mediated transfers. Although direct insertion of mitochondrial DNA into the nucleus occurs frequently in angiosperms, case studies of functional mitochondrial gene transfer have implicated an RNA-mediated mechanism that eliminates introns and RNA editing sites, which would otherwise impede proper expression of mitochondrial genes in the nucleus. To elucidate the mechanisms that facilitate functional gene transfers and the evolutionary dynamics of the coexisting nuclear and mitochondrial gene copies that are established during these transfers, we have analyzed rpl5 genes from 90 grasses (Poaceae) and related monocots. Multiple lines of evidence indicate that rpl5 has been functionally transferred to the nucleus at least three separate times in the grass family and that at least seven species have intact and transcribed (but not necessarily functional) copies in both the mitochondrion and nucleus. In two grasses, likely functional nuclear copies of rpl5 have been subject to recent gene conversion events via secondarily transferred mitochondrial copies in what we believe are the first described cases of mitochondrial-to-nuclear gene conversion. We show that rpl5 underwent a retroprocessing event within the mitochondrial genome early in the evolution of the grass family, which we argue predisposed the gene towards successful, DNA-mediated functional transfer by generating a "pre-edited" sequence.
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Affiliation(s)
- Zhiqiang Wu
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Daniel B. Sloan
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Colin W. Brown
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX
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21
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Kang X, Hu L, Shen P, Li R, Liu D. SMRT Sequencing Revealed Mitogenome Characteristics and Mitogenome-Wide DNA Modification Pattern in Ophiocordyceps sinensis. Front Microbiol 2017; 8:1422. [PMID: 28798740 PMCID: PMC5529405 DOI: 10.3389/fmicb.2017.01422] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/13/2017] [Indexed: 11/24/2022] Open
Abstract
Single molecule, real-time (SMRT) sequencing was used to characterize mitochondrial (mt) genome of Ophiocordyceps sinensis and to analyze the mt genome-wide pattern of epigenetic DNA modification. The complete mt genome of O. sinensis, with a size of 157,539 bp, is the fourth largest Ascomycota mt genome sequenced to date. It contained 14 conserved protein-coding genes (PCGs), 1 intronic protein rps3, 27 tRNAs and 2 rRNA subunits, which are common characteristics of the known mt genomes in Hypocreales. A phylogenetic tree inferred from 14 PCGs in Pezizomycotina fungi supports O. sinensis as most closely related to Hirsutella rhossiliensis in Ophiocordycipitaceae. A total of 36 sequence sites in rps3 were under positive selection, with dN/dS >1 in the 20 compared fungi. Among them, 16 sites were statistically significant. In addition, the mt genome-wide base modification pattern of O. sinensis was determined in this study, especially DNA methylation. The methylations were located in coding and uncoding regions of mt PCGs in O. sinensis, and might be closely related to the expression of PCGs or the binding affinity of transcription factor A to mtDNA. Consequently, these methylations may affect the enzymatic activity of oxidative phosphorylation and then the mt respiratory rate; or they may influence mt biogenesis. Therefore, methylations in the mitogenome of O. sinensis might be a genetic feature to adapt to the cold and low PO2 environment at high altitude, where O. sinensis is endemic. This is the first report on epigenetic modifications in a fungal mt genome.
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Affiliation(s)
- Xincong Kang
- Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural UniversityChangsha, China
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
| | - Liqin Hu
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
| | - Pengyuan Shen
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
| | - Rui Li
- Nextomics BiosciencesWuhan, China
| | - Dongbo Liu
- Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural UniversityChangsha, China
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
- Hunan Co-Innovation Center for Utilization of Botanical Functional IngredientsChangsha, China
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22
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Petersen G, Cuenca A, Zervas A, Ross GT, Graham SW, Barrett CF, Davis JI, Seberg O. Mitochondrial genome evolution in Alismatales: Size reduction and extensive loss of ribosomal protein genes. PLoS One 2017; 12:e0177606. [PMID: 28545148 PMCID: PMC5435185 DOI: 10.1371/journal.pone.0177606] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 04/28/2017] [Indexed: 11/18/2022] Open
Abstract
The order Alismatales is a hotspot for evolution of plant mitochondrial genomes characterized by remarkable differences in genome size, substitution rates, RNA editing, retrotranscription, gene loss and intron loss. Here we have sequenced the complete mitogenomes of Zostera marina and Stratiotes aloides, which together with previously sequenced mitogenomes from Butomus and Spirodela, provide new evolutionary evidence of genome size reduction, gene loss and transfer to the nucleus. The Zostera mitogenome includes a large portion of DNA transferred from the plastome, yet it is the smallest known mitogenome from a non-parasitic plant. Using a broad sample of the Alismatales, the evolutionary history of ribosomal protein gene loss is analyzed. In Zostera almost all ribosomal protein genes are lost from the mitogenome, but only some can be found in the nucleus.
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Affiliation(s)
- Gitte Petersen
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Argelia Cuenca
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Athanasios Zervas
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Gregory T. Ross
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- UBC Botanical Garden & Centre for Plant Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sean W. Graham
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- UBC Botanical Garden & Centre for Plant Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Craig F. Barrett
- L. H. Bailey Hortorium and Plant Biology Section, Cornell University, Ithaca, New York, United States of America
| | - Jerrold I. Davis
- L. H. Bailey Hortorium and Plant Biology Section, Cornell University, Ithaca, New York, United States of America
| | - Ole Seberg
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
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