1
|
He Y, Liu W, Wang J. Assembly and comparative analysis of the complete mitochondrial genome of Trigonella foenum-graecum L. BMC Genomics 2023; 24:756. [PMID: 38066419 PMCID: PMC10704837 DOI: 10.1186/s12864-023-09865-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND Trigonella foenum-graecum L. is a Leguminosae plant, and the stems, leaves, and seeds of this plant are rich in chemical components that are of high research value. The chloroplast (cp) genome of T. foenum-graecum has been reported, but the mitochondrial (mt) genome remains unexplored. RESULTS In this study, we used second- and third-generation sequencing methods, which have the dual advantage of combining high accuracy and longer read length. The results showed that the mt genome of T. foenum-graecum was 345,604 bp in length and 45.28% in GC content. There were 59 genes, including: 33 protein-coding genes (PCGs), 21 tRNA genes, 4 rRNA genes and 1 pseudo gene. Among them, 11 genes contained introns. The mt genome codons of T. foenum-graecum had a significant A/T preference. A total of 202 dispersed repetitive sequences, 96 simple repetitive sequences (SSRs) and 19 tandem repetitive sequences were detected. Nucleotide diversity (Pi) analysis counted the variation in each gene, with atp6 being the most notable. Both synteny and phylogenetic analyses showed close genetic relationship among Trifolium pratense, Trifolium meduseum, Trifolium grandiflorum, Trifolium aureum, Medicago truncatula and T. foenum-graecum. Notably, in the phylogenetic tree, Medicago truncatula demonstrated the highest level of genetic relatedness to T. foenum-graecum, with a strong support value of 100%. The interspecies non-synonymous substitutions (Ka)/synonymous substitutions (Ks) results showed that 23 PCGs had Ka/Ks < 1, indicating that these genes would continue to evolve under purifying selection pressure. In addition, setting the similarity at 70%, 23 homologous sequences were found in the mt genome of T. foenum-graecum. CONCLUSIONS This study explores the mt genome sequence information of T. foenum-graecum and complements our knowledge of the phylogenetic diversity of Leguminosae plants.
Collapse
Affiliation(s)
- Yanfeng He
- College of Pharmacy, Qinghai Minzu University, Xining, 810007, Qinghai, China
| | - Wenya Liu
- College of Pharmacy, Qinghai Minzu University, Xining, 810007, Qinghai, China
| | - Jiuli Wang
- The College of Ecological Environment and Resources, Qinghai Minzu University, Xining, 810007, Qinghai, China.
| |
Collapse
|
2
|
Mizrahi R, Shevtsov-Tal S, Ostersetzer-Biran O. Group II Intron-Encoded Proteins (IEPs/Maturases) as Key Regulators of Nad1 Expression and Complex I Biogenesis in Land Plant Mitochondria. Genes (Basel) 2022; 13:genes13071137. [PMID: 35885919 PMCID: PMC9321910 DOI: 10.3390/genes13071137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 06/15/2022] [Accepted: 06/22/2022] [Indexed: 02/04/2023] Open
Abstract
Mitochondria are semi-autonomous organelles that produce much of the energy required for cellular metabolism. As descendants of a bacterial symbiont, most mitochondria harbor their own genetic system (mtDNA/mitogenome), with intrinsic machineries for transcription and protein translation. A notable feature of plant mitochondria involves the presence of introns (mostly group II-type) that reside in many organellar genes. The splicing of the mtRNAs relies on the activities of various protein cofactors, which may also link organellar functions with cellular or environmental signals. The splicing of canonical group II introns is aided by an ancient class of RT-like enzymes (IEPs/maturases, MATs) that are encoded by the introns themselves and act specifically on their host introns. The plant organellar introns are degenerated in structure and are generally also missing their cognate intron-encoded proteins. The factors required for plant mtRNA processing are mostly nuclearly-encoded, with the exception of a few degenerated MATs. These are in particular pivotal for the maturation of NADH-dehydrogenase transcripts. In the following review we provide an update on the non-canonical MAT factors in angiosperm mitochondria and summarize the current knowledge of their essential roles in regulating Nad1 expression and complex I (CI) biogenesis during embryogenesis and early plant life.
Collapse
|
3
|
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: 69] [Impact Index Per Article: 11.5] [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.
Collapse
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
| |
Collapse
|
4
|
Farré JC, Aknin C, Araya A, Castandet B. RNA editing in mitochondrial trans-introns is required for splicing. PLoS One 2012; 7:e52644. [PMID: 23285127 PMCID: PMC3527595 DOI: 10.1371/journal.pone.0052644] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/19/2012] [Indexed: 11/29/2022] Open
Abstract
In plant mitochondria, gene expression of translatable mRNAs is a complex process with two critical steps, RNA editing and splicing. We studied the role of RNA editing on non-coding regions of the mat-r-nad1e-nad5c transcript from wheat mitochondria. This RNA contains two trans-introns, 3'-nad1-I4 and 3'-nad5-I2, involved in different trans-splicing events, ensuring the association of nad1d-nad1e and nad5b-nad5c exons from nad1 and nad5 mRNAs respectively. The C-to-U editing changes studied here affect homologous positions on 3'-nad1-I4 and 3'-nad5-I2. It is proposed that these base changes are necessary to place an Adenosine residue in a bulging conformation characteristic of domain VI (D6) from group II introns. In this work, we investigated the role of RNA editing events on 3'-nad1-I4 and 3'-nad5-I2 in the trans-splicing process using in vivo and in organello approaches. When the branched intermediates formed during the splicing process were analyzed, the C residues from D6 intron domains from 3'-nad1-I4 and 3'-nad5-I2 were found changed to U, suggesting that RNA editing of these residues could be mandatory for splicing. This assumption was tested by expressing recombinant mat-r-nad1e transgenes introduced into mitochondria by electroporation. Mutation of the editing target residue dramatically affected trans-splicing. Interestingly, the exon joining efficiency was not recovered by compensatory mutations, suggesting that the role of RNA editing is not confined to the restoration of the secondary structure of domain D6 of the intron. Our results strongly support the hypothesis that RNA editing in trans-introns precedes maturation, and is required for the splicing reaction. In addition, this is the first report using an in organello approach to study the trans-splicing process, opening the way to future studies of this peculiar mechanism.
Collapse
Affiliation(s)
- Jean-Claude Farré
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
| | - Cindy Aknin
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
| | - Alejandro Araya
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
- Institut de Biologie Végétale Moléculaire, UMR1332 Biologie du Fruit et Pathologie, Centre INRA de Bordeaux, Vilenave d'Ornon, France
- * E-mail:
| | - Benoît Castandet
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
| |
Collapse
|
5
|
Marfil CF, Camadro EL, Masuelli RW. Phenotypic instability and epigenetic variability in a diploid potato of hybrid origin, Solanum ruiz-lealii. BMC PLANT BIOLOGY 2009; 9:21. [PMID: 19232108 PMCID: PMC2656509 DOI: 10.1186/1471-2229-9-21] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 02/20/2009] [Indexed: 05/05/2023]
Abstract
BACKGROUND The wild potato Solanum ruiz-lealii Brüch. (2n = 2x = 24), a species of hybrid origin, is endemic to Mendoza province, Argentina. Recurrent flower malformations, which varied among inflorescences of the same plant, were observed in a natural population. These abnormalities could be the result of genomic instabilities, nucleus-cytoplasmic incompatibility or epigenetic changes. To shed some light on their origin, nuclear and mitochondrial DNA of plants with normal and plants with both normal and malformed flowers (from here on designated as plants with normal and plants with abnormal flower phenotypes, respectively) were analyzed by AFLP and restriction analyses, respectively. Also, the wide genome methylation status and the level of methylation of a repetitive sequence were studied by MSAP and Southern blots analyses, respectively. RESULTS AFLP markers and restriction patterns of mitochondrial DNA did not allow the differentiation of normal from abnormal flower phenotypes. However, methylation patterns of nuclear DNA discriminated normal and abnormal flower phenotypes into two different groups, indicating that abnormal phenotypes have a similar methylation status which, in turn, was different from the methylation patterns of normal phenotypes. The abnormal flower phenotype was obtained by treating a normal plant with 5-Azacytidine, a demethylating agent, giving support to the idea of the role of DNA methylation in the origin of flower abnormalities. In addition, the variability detected for DNA methylation was greater than the detected for nucleotide sequence. CONCLUSION The epigenetic nature of the observed flower abnormalities is consistent with the results and indicates that in the diploid hybrid studied, natural variation in methylation profiles of anonymous DNA sequences could be of biological significance.
Collapse
Affiliation(s)
- Carlos F Marfil
- Laboratorio de Biología Molecular, EEA La Consulta INTA, Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo and CONICET, M5528AHB, Alte. Brown 500, Chacras de Coria Mendoza, Argentina
| | - Elsa L Camadro
- EEA Balcarce, INTA-FCA, UNMdP and CONICET, CC 276, 7620, Balcarce, Bs. As., Argentina
| | - Ricardo W Masuelli
- Laboratorio de Biología Molecular, EEA La Consulta INTA, Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo and CONICET, M5528AHB, Alte. Brown 500, Chacras de Coria Mendoza, Argentina
| |
Collapse
|
6
|
The horsetail Equisetum arvense mitochondria share two group I introns with the liverwort Marchantia, acquired a novel group II intron but lost intron-encoded ORFs. Curr Genet 2008; 55:69-79. [PMID: 19112563 DOI: 10.1007/s00294-008-0225-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 12/05/2008] [Accepted: 12/05/2008] [Indexed: 12/16/2022]
Abstract
We studied the genomic structure and RNA editing of mitochondrial cox1, cox2, cob and atp9 from the horsetail Equisetum arvense, a representative of an old fern lineage. Editing of cox1, cob and atp9 mRNAs occur only by C-to-U transitions. No changes were found in cox2 transcripts constituting one of the rare examples of unedited mitochondrial mRNA in land plants. From three intervening sequences in cox1, cox1i395 and cox1i624 are group IB introns homologous to the Marchantia polymorpha cox1 introns, and cox1i747 is a group IIA intron different to other introns found in plant mtDNA. The group II intron cox2i373 is very similar to other introns found in cox2 from vascular plants. While cob and atp9 have no introns and display the gene structure found in seed plants, various nucleotide substitutions abolish the only potential ORF, a LAGLIDADG endonuclease present in cox1i395. Thus, E. arvense mitochondria conserve two group I introns from non-vascular plants, probably inherited from a common ancestor with liverworts. Analogous to seed plants, E. arvense has no potential mitochondrial splicing factors encoded in these introns. This is the first report concerning the presence of vertically inherited group I introns in vascular plant mitochondria.
Collapse
|
7
|
Tsunewaki K, Matsuoka Y, Yamazaki Y, Ogihara Y. Evolutionary dynamics of wheat mitochondrial gene structure with special remarks on the origin and effects of RNA editing in cereals. Genes Genet Syst 2008; 83:301-20. [PMID: 18931456 DOI: 10.1266/ggs.83.301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We investigated the evolutionary dynamics of wheat mitochondrial genes with respect to their structural differentiation during organellar evolution, and to mutations that occurred during cereal evolution. First, we compared the nucleotide sequences of three wheat mitochondrial genes to those of wheat chloroplast, alpha-proteobacterium and cyanobacterium orthologs. As a result, we were able to (1) differentiate the conserved and variable segments of the orthologs, (2) reveal the functional importance of the conserved segments, and (3) provide a corroborative support for the alpha-proteobacterial and cyanobacterial origins of those mitochondrial and chloroplast genes, respectively. Second, we compared the nucleotide sequences of wheat mitochondrial genes to those of rice and maize to determine the types and frequencies of base changes and indels occurred in cereal evolution. Our analyses showed that both the evolutionary speed, in terms of number of base substitutions per site, and the transition/transversion ratio of the cereal mitochondrial genes were less than two-fifths of those of the chloroplast genes. Eight mitochondrial gene groups differed in their evolutionary variability, RNA and Complex I (nad) genes being most stable whereas Complex V (atp) and ribosomal protein genes most variable. C-to-T transition was the most frequent type of base change; C-to-G and G-to-C transversions occurred at lower rates than all other changes. The excess of C-to-T transitions was attributed to C-to-U RNA editing that developed in early stage of vascular plant evolution. On the contrary, the editing of C residues at cereal T-to-C transition sites developed mostly during cereal divergence. Most indels were associated with short direct repeats, suggesting intra- and intermolecular recombination as an important mechanism for their origin. Most of the repeats associated with indels were di- or trinucleotides, although no preference was noticed for their sequences. The maize mt genome was characterized by a high incidence of indels, comparing to the wheat and rice mt genomes.
Collapse
|
8
|
Mitochondrial matR sequences help to resolve deep phylogenetic relationships in rosids. BMC Evol Biol 2007; 7:217. [PMID: 17996110 PMCID: PMC2222252 DOI: 10.1186/1471-2148-7-217] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Accepted: 11/10/2007] [Indexed: 12/03/2022] Open
Abstract
Background Rosids are a major clade in the angiosperms containing 13 orders and about one-third of angiosperm species. Recent molecular analyses recognized two major groups (i.e., fabids with seven orders and malvids with three orders). However, phylogenetic relationships within the two groups and among fabids, malvids, and potentially basal rosids including Geraniales, Myrtales, and Crossosomatales remain to be resolved with more data and a broader taxon sampling. In this study, we obtained DNA sequences of the mitochondrial matR gene from 174 species representing 72 families of putative rosids and examined phylogenetic relationships and phylogenetic utility of matR in rosids. We also inferred phylogenetic relationships within the "rosid clade" based on a combined data set of 91 taxa and four genes including matR, two plastid genes (rbcL, atpB), and one nuclear gene (18S rDNA). Results Comparison of mitochondrial matR and two plastid genes (rbcL and atpB) showed that the synonymous substitution rate in matR was approximately four times slower than those of rbcL and atpB; however, the nonsynonymous substitution rate in matR was relatively high, close to its synonymous substitution rate, indicating that the matR has experienced a relaxed evolutionary history. Analyses of our matR sequences supported the monophyly of malvids and most orders of the rosids. However, fabids did not form a clade; instead, the COM clade of fabids (Celastrales, Oxalidales, Malpighiales, and Huaceae) was sister to malvids. Analyses of the four-gene data set suggested that Geraniales and Myrtales were successively sister to other rosids, and that Crossosomatales were sister to malvids. Conclusion Compared to plastid genes such as rbcL and atpB, slowly evolving matR produced less homoplasious but not less informative substitutions. Thus, matR appears useful in higher-level angiosperm phylogenetics. Analysis of matR alone identified a novel deep relationship within rosids, the grouping of the COM clade of fabids and malvids, which was not resolved by any previous molecular analyses but recently suggested by floral structural features. Our four-gene analysis supported the placements of Geraniales, Myrtales at basal nodes of the rosid clade and placed Crossosomatales as sister to malvids. We also suggest that the core part of rosids should include fabids, malvids and Crossosomatales.
Collapse
|
9
|
Mulligan RM, Chang KLC, Chou CC. Computational analysis of RNA editing sites in plant mitochondrial genomes reveals similar information content and a sporadic distribution of editing sites. Mol Biol Evol 2007; 24:1971-81. [PMID: 17591603 DOI: 10.1093/molbev/msm125] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A computational analysis of RNA editing sites was performed on protein-coding sequences of plant mitochondrial genomes from Arabidopsis thaliana, Beta vulgaris, Brassica napus, and Oryza sativa. The distribution of nucleotides around edited and unedited cytidines was compared in 41 nucleotide segments and included 1481 edited cytidines and 21,390 unedited cytidines in the 4 genomes. The distribution of nucleotides was examined in 1, 2, and 3 nucleotide windows by comparison of nucleotide frequency ratios and relative entropy. The relative entropy analyses indicate that information is encoded in the nucleotide sequences in the 5 prime flank (-18 to -14, -13 to -10, -6 to -4, -2/-1) and the immediate 3 prime flanking nucleotide (+1), and these regions may be important in editing site recognition. The relative entropy was large when 2 or 3 nucleotide windows were analyzed, suggesting that several contiguous nucleotides may be involved in editing site recognition. RNA editing sites were frequently preceded by 2 pyrimidines or AU and followed by a guanidine (HYCG) in the monocot and dicot mitochondrial genomes, and rarely preceded by 2 purines. Analysis of chloroplast editing sites from a dicot, Nicotiana tabacum, and a monocot, Zea mays, revealed a similar distribution of nucleotides around editing sites (HYCA). The similarity of this motif around editing sites in monocots and dicots in both mitochondria and chloroplasts suggests that a mechanistic basis for this motif exists that is common in these different organelle and phylogenetic systems. The preferred sequence distribution around RNA editing sites may have an important impact on the acquisition of editing sites in evolution because the immediate sequence context of a cytidine residue may render a cytidine editable or uneditable, and consequently determine whether a T to C mutation at a specific position may be corrected by RNA editing. The distribution of editing sites in many protein-coding sequences is shown to be non-random with editing sites clustered in groups separated by regions with no editing sites. The sporadic distribution of editing sites could result from a mechanism of editing site loss by gene conversion utilizing edited sequence information, possibly through an edited cDNA intermediate.
Collapse
Affiliation(s)
- R Michael Mulligan
- Department of Developmental and Cell Biology, University of California, Irvine, USA.
| | | | | |
Collapse
|
10
|
Mower JP, Palmer JD. Patterns of partial RNA editing in mitochondrial genes of Beta vulgaris. Mol Genet Genomics 2006; 276:285-93. [PMID: 16862402 DOI: 10.1007/s00438-006-0139-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 05/23/2006] [Indexed: 11/27/2022]
Abstract
RNA editing is a process that modifies the information in transcripts of almost all angiosperm mitochondrial protein-coding genes. In order to determine the frequency and distribution of mitochondrial RNA editing in Beta vulgaris, cDNAs were sequenced and compared to the published genome sequence. 357 C to U conversions were identified across the 31 known protein genes and pseudogenes in Beta, the fewest so far for a plant mitochondrial genome. Editing patterns in the putative gene orf518 indicate that it is most likely a functional ccmC homolog, indicating that patterns of editing can be a useful determinant of gene functionality. orf518 also contains a triplicated repeat region whose members are nearly identical yet differentially edited, most likely due to differences in the sequence context of the editing sites. In addition, we show that partial editing in Beta is common at silent editing sites but rare at nonsilent editing sites, extending previous observations to a complete plant mitochondrial genome. Finally, the degree of partial editing observed for certain genes was dependent on the choice of primers used, demonstrating that care must be taken when designing primers for use in editing studies.
Collapse
Affiliation(s)
- Jeffrey P Mower
- Department of Biology, Indiana University, Bloomington, IN 47405, USA. [corrected]
| | | |
Collapse
|
11
|
Barkman TJ, Lim SH, Salleh KM, Nais J. Mitochondrial DNA sequences reveal the photosynthetic relatives of Rafflesia, the world's largest flower. Proc Natl Acad Sci U S A 2004; 101:787-92. [PMID: 14715901 PMCID: PMC321759 DOI: 10.1073/pnas.0305562101] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Indexed: 11/18/2022] Open
Abstract
All parasites are thought to have evolved from free-living ancestors. However, the ancestral conditions facilitating the shift to parasitism are unclear, particularly in plants because the phylogenetic position of many parasites is unknown. This is especially true for Rafflesia, an endophytic holoparasite that produces the largest flowers in the world and has defied confident phylogenetic placement since its discovery >180 years ago. Here we present results of a phylogenetic analysis of 95 species of seed plants designed to infer the position of Rafflesia in an evolutionary context using the mitochondrial gene matR (1,806 aligned base pairs). Overall, the estimated phylogenetic tree is highly congruent with independent analyses and provides a strongly supported placement of Rafflesia with the order Malpighiales, which includes poinsettias, violets, and passionflowers. Furthermore, the phylogenetic placement of Mitrastema, another enigmatic, holoparasitic angiosperm with the order Ericales (which includes blueberries and persimmons), was obtained with these data. Although traditionally classified together, Rafflesia and Mitrastema are only distantly related, implying that their endoparasitic habits result from convergent evolution. Our results indicate that the previous significant difficulties associated with phylogenetic placement of holoparasitic plants may be overcome by using mitochondrial DNA so that a broader understanding of the origins and evolution of parasitism may emerge.
Collapse
Affiliation(s)
- Todd J Barkman
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA.
| | | | | | | |
Collapse
|
12
|
|
13
|
Farré JC, Araya A. Gene expression in isolated plant mitochondria: high fidelity of transcription, splicing and editing of a transgene product in electroporated organelles. Nucleic Acids Res 2001; 29:2484-91. [PMID: 11410655 PMCID: PMC55745 DOI: 10.1093/nar/29.12.2484] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial gene expression was studied using an electrotransformation protocol to introduce foreign DNA into purified wheat mitochondria. Optimal conditions for DNA uptake and transient gene expression were determined. We show here that a DNA plasmid containing either a cognate or a non-cognate gene under the control of a plant mitochondrial promoter is incorporated into the organelle and faithfully recognized by the transcription machinery. Transcripts generated by a plasmid bearing the intron-containing cox II gene were correctly spliced. Moreover, the transcripts were edited at the expected target C residues. The expression and maturation process of the transgene is dependent on the integrity of functional elements such as the promotor or the presence of structural domains necessary for splicing. The mitochondrial transformation described in this report is an important tool to study the multiple steps involved in plant mitochondrial gene expression at conditions closer to those found in vivo.
Collapse
MESH Headings
- Base Sequence
- DNA, Mitochondrial/genetics
- DNA, Plant/genetics
- DNA, Recombinant/genetics
- Deoxyribonuclease I/metabolism
- Electron Transport Complex IV/genetics
- Electroporation/methods
- Gene Expression Regulation, Plant
- Genes, Reporter/genetics
- Introns/genetics
- Kinetics
- Magnoliopsida/cytology
- Magnoliopsida/embryology
- Magnoliopsida/genetics
- Mitochondria/genetics
- Nucleic Acid Conformation
- Plasmids/genetics
- Promoter Regions, Genetic/genetics
- RNA Editing/genetics
- RNA Splicing/genetics
- RNA Stability/genetics
- RNA, Plant/chemistry
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Transcription, Genetic/genetics
- Transformation, Genetic
- Transgenes/genetics
Collapse
Affiliation(s)
- J C Farré
- Laboratoire de Réplication et Expression des Gènes Eucaryotes et Rétroviraux, UMR 5097, Centre National de la Recherche Scientifique and Université Victor Segalen-Bordeaux 2, 146 rue Leo Saignat, 33076 Bordeaux Cedex, France
| | | |
Collapse
|