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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.
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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.
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2
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Zu X, Luo L, Wang Z, Gong J, Yang C, Wang Y, Xu C, Qiao X, Deng X, Song X, Chen C, Tan BC, Cao X. A mitochondrial pentatricopeptide repeat protein enhances cold tolerance by modulating mitochondrial superoxide in rice. Nat Commun 2023; 14:6789. [PMID: 37880207 PMCID: PMC10600133 DOI: 10.1038/s41467-023-42269-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 10/04/2023] [Indexed: 10/27/2023] Open
Abstract
Cold stress affects rice growth and productivity. Defects in the plastid-localized pseudouridine synthase OsPUS1 affect chloroplast ribosome biogenesis, leading to low-temperature albino seedlings and accumulation of reactive oxygen species (ROS). Here, we report an ospus1-1 suppressor, sop10. SOP10 encodes a mitochondria-localized pentatricopeptide repeat protein. Mutations in SOP10 impair intron splicing of the nad4 and nad5 transcripts and decrease RNA editing efficiency of the nad2, nad6, and rps4 transcripts, resulting in deficiencies in mitochondrial complex I, thus decrease ROS generation and rescuing the albino phenotype. Overexpression of different compartment-localized superoxide dismutases (SOD) genes in ospus1-1 reverses the ROS over-accumulation and albino phenotypes to various degrees, with Mn-SOD reversing the best. Mutation of SOP10 in indica rice varieties enhances cold tolerance with lower ROS levels. We find that the mitochondrial superoxide plays a key role in rice cold responses, and identify a mitochondrial superoxide modulating factor, informing efforts to improve rice cold tolerance.
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Affiliation(s)
- Xiaofeng Zu
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Lilan Luo
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Zhen Wang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jie Gong
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
- The Municipal Key Laboratory of the Molecular Genetics of Hybrid Wheat, Institute of Hybrid Wheat, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
| | - Chao Yang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yong Wang
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Chunhui Xu
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Xinhua Qiao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xian Deng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xianwei Song
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chang Chen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Bao-Cai Tan
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Xiaofeng Cao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Beijing, 100101, China.
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3
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Zumkeller S, Knoop V. Categorizing 161 plant (streptophyte) mitochondrial group II introns into 29 families of related paralogues finds only limited links between intron mobility and intron-borne maturases. BMC Ecol Evol 2023; 23:5. [PMID: 36915058 PMCID: PMC10012718 DOI: 10.1186/s12862-023-02108-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 02/27/2023] [Indexed: 03/14/2023] Open
Abstract
Group II introns are common in the two endosymbiotic organelle genomes of the plant lineage. Chloroplasts harbor 22 positionally conserved group II introns whereas their occurrence in land plant (embryophyte) mitogenomes is highly variable and specific for the seven major clades: liverworts, mosses, hornworts, lycophytes, ferns, gymnosperms and flowering plants. Each plant group features "signature selections" of ca. 20-30 paralogues from a superset of altogether 105 group II introns meantime identified in embryophyte mtDNAs, suggesting massive intron gains and losses along the backbone of plant phylogeny. We report on systematically categorizing plant mitochondrial group II introns into "families", comprising evidently related paralogues at different insertion sites, which may even be more similar than their respective orthologues in phylogenetically distant taxa. Including streptophyte (charophyte) algae extends our sampling to 161 and we sort 104 streptophyte mitochondrial group II introns into 25 core families of related paralogues evidently arising from retrotransposition events. Adding to discoveries of only recently created intron paralogues, hypermobile introns and twintrons, our survey led to further discoveries including previously overlooked "fossil" introns in spacer regions or e.g., in the rps8 pseudogene of lycophytes. Initially excluding intron-borne maturase sequences for family categorization, we added an independent analysis of maturase phylogenies and find a surprising incongruence between intron mobility and the presence of intron-borne maturases. Intriguingly, however, we find that several examples of nuclear splicing factors meantime characterized simultaneously facilitate splicing of independent paralogues now placed into the same intron families. Altogether this suggests that plant group II intron mobility, in contrast to their bacterial counterparts, is not intimately linked to intron-encoded maturases.
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Affiliation(s)
- Simon Zumkeller
- IZMB, Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Volker Knoop
- IZMB, Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115, Bonn, Germany.
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4
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Yang H, Chen H, Ni Y, Li J, Cai Y, Wang J, Liu C. Mitochondrial Genome Sequence of Salvia officinalis (Lamiales: Lamiaceae) Suggests Diverse Genome Structures in Cogeneric Species and Finds the Stop Gain of Genes through RNA Editing Events. Int J Mol Sci 2023; 24:ijms24065372. [PMID: 36982448 PMCID: PMC10048906 DOI: 10.3390/ijms24065372] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/20/2023] [Accepted: 03/02/2023] [Indexed: 03/14/2023] Open
Abstract
Our previous study was the first to confirm that the predominant conformation of mitochondrial genome (mitogenome) sequence of Salvia species contains two circular chromosomes. To further understand the organization, variation, and evolution of Salvia mitogenomes, we characterized the mitogenome of Salvia officinalis. The mitogenome of S. officinalis was sequenced using Illumina short reads and Nanopore long reads and assembled using a hybrid assembly strategy. We found that the predominant conformation of the S. officinalis mitogenome also had two circular chromosomes that were 268,341 bp (MC1) and 39,827 bp (MC2) in length. The S. officinalis mitogenome encoded an angiosperm-typical set of 24 core genes, 9 variable genes, 3 rRNA genes, and 16 tRNA genes. We found many rearrangements of the Salvia mitogenome through inter- and intra-specific comparisons. A phylogenetic analysis of the coding sequences (CDs) of 26 common protein-coding genes (PCGs) of 11 Lamiales species and 2 outgroup taxa strongly indicated that the S. officinalis was a sister taxon to S. miltiorrhiza, consistent with the results obtained using concatenated CDs of common plastid genes. The mapping of RNA-seq data to the CDs of PCGs led to the identification of 451 C-to-U RNA editing sites from 31 PCGs of the S. officinalis mitogenome. Using PCR amplification and Sanger sequencing methods, we successfully validated 113 of the 126 RNA editing sites from 11 PCGs. The results of this study suggest that the predominant conformation of the S. officinalis mitogenome are two circular chromosomes, and the stop gain of rpl5 was found through RNA editing events of the Salvia mitogenome.
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Affiliation(s)
- Heyu Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Haimei Chen
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Yang Ni
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Jingling Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Yisha Cai
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Jiehua Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
- Correspondence: (J.W.); (C.L.); Tel.: +86-022-8740-2072 (J.W.); +86-10-5783-3111 (C.L.); Fax: +86-022-2740-7956 (J.W.); +86-10-62899715 (C.L.)
| | - Chang Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
- Correspondence: (J.W.); (C.L.); Tel.: +86-022-8740-2072 (J.W.); +86-10-5783-3111 (C.L.); Fax: +86-022-2740-7956 (J.W.); +86-10-62899715 (C.L.)
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5
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Li J, Xu Y, Shan Y, Pei X, Yong S, Liu C, Yu J. Assembly of the complete mitochondrial genome of an endemic plant, Scutellaria tsinyunensis, revealed the existence of two conformations generated by a repeat-mediated recombination. PLANTA 2021; 254:36. [PMID: 34302538 DOI: 10.1007/s00425-021-03684-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
We assembled the complete mitochondrial genome of Scutellaria tsinyunensis in this study. Repeat-mediated recombination resulted in the formation of two conformations of the mitochondrial genome in S. tsinyunensis. Scutellaria tsinyunensis belongs to the family Lamiaceae, distributed only in the Jinyun Mountain, Chongqing, China. As a valuable endemic and small population species, it is regarded as a natural resource potentially with significant economic and ecological importance. In this study, we assembled a complete and gap-free mitochondrial genome of S. tsinyunensis. This genome had a length of 354,073 bp and the base composition of the genome was A (27.44%), T (27.30%), C (22.58%), and G (22.68%). This genome encodes 59 genes, including 32 protein-coding genes, 24 tRNA genes, and 3 rRNA genes. The Sanger sequencing and Oxford Nanopore sequencing confirmed a pair of direct repeats had mediated genome recombination, resulting in the formation of two conformations. The gene conversation between plastome and mitochondrial genome was also observed in S. tsinyunensis by detecting gene migration, including six tRNA genes (namely, trnW-CCA, trnI-CAU, trnH-UUU, trnD-GUC, trnN-GUU, and trnM-CAU), five protein-coding gene fragments, and the fragments from 2 rRNA genes. Moreover, the dN/dS analysis revealed the atp9 gene had undergone strong negative selection, and four genes (atp4, mttB, ccmFc, and ccmB) probably had undergone positive selection during evolution in Lamiales. This work reported the first mitochondrial genome of S. tsinyunensis, which could be used as a reference genome for the important medicinal plants of the genus Scutellaria, and also provide much-desired information for molecular breeding.
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Affiliation(s)
- Jingling Li
- Key Laboratory of Horticulture Science for Southern Mountainous Regions from Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing, 400716, China
| | - Yicen Xu
- Key Laboratory of Horticulture Science for Southern Mountainous Regions from Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing, 400716, China
| | - Yuanyu Shan
- Key Laboratory of Horticulture Science for Southern Mountainous Regions from Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing, 400716, China
| | - Xiaoying Pei
- Key Laboratory of Horticulture Science for Southern Mountainous Regions from Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing, 400716, China
| | - Shunyuan Yong
- Key Laboratory of Horticulture Science for Southern Mountainous Regions from Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing, 400716, China
| | - Chang Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing, 100093, People's Republic of China.
| | - Jie Yu
- Key Laboratory of Horticulture Science for Southern Mountainous Regions from Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing, 400716, China.
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6
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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: 55] [Impact Index Per Article: 13.8] [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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7
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Zumkeller S, Gerke P, Knoop V. A functional twintron, 'zombie' twintrons and a hypermobile group II intron invading itself in plant mitochondria. Nucleic Acids Res 2020; 48:2661-2675. [PMID: 31915815 PMCID: PMC7049729 DOI: 10.1093/nar/gkz1194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/26/2019] [Accepted: 12/11/2019] [Indexed: 02/06/2023] Open
Abstract
The occurrence of group II introns in plant mitochondrial genomes is strikingly different between the six major land plant clades, contrasting their highly conserved counterparts in chloroplast DNA. Their present distribution likely reflects numerous ancient intron gains and losses during early plant evolution before the emergence of seed plants. As a novelty for plant organelles, we here report on five cases of twintrons, introns-within-introns, in the mitogenomes of lycophytes and hornworts. An internal group II intron interrupts an intron-borne maturase of an atp9 intron in Lycopodiaceae, whose splicing precedes splicing of the external intron. An invasive, hypermobile group II intron in cox1, has conquered nine further locations including a previously overlooked sdh3 intron and, most surprisingly, also itself. In those cases, splicing of the external introns does not depend on splicing of the internal introns. Similar cases are identified in the mtDNAs of hornworts. Although disrupting a group I intron-encoded protein in one case, we could not detect splicing of the internal group II intron in this ‘mixed’ group I/II twintron. We suggest the name ‘zombie’ twintrons (half-dead, half-alive) for such cases where splicing of external introns does not depend any more on prior splicing of fossilized internal introns.
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Affiliation(s)
- Simon Zumkeller
- IZMB - Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
| | - Philipp Gerke
- IZMB - Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
| | - Volker Knoop
- IZMB - Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
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8
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Gerke P, Szövényi P, Neubauer A, Lenz H, Gutmann B, McDowell R, Small I, Schallenberg-Rüdinger M, Knoop V. Towards a plant model for enigmatic U-to-C RNA editing: the organelle genomes, transcriptomes, editomes and candidate RNA editing factors in the hornwort Anthoceros agrestis. THE NEW PHYTOLOGIST 2020; 225:1974-1992. [PMID: 31667843 DOI: 10.1111/nph.16297] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 10/20/2019] [Indexed: 06/10/2023]
Abstract
Hornworts are crucial to understand the phylogeny of early land plants. The emergence of 'reverse' U-to-C RNA editing accompanying the widespread C-to-U RNA editing in plant chloroplasts and mitochondria may be a molecular synapomorphy of a hornwort-tracheophyte clade. C-to-U RNA editing is well understood after identification of many editing factors in models like Arabidopsis thaliana and Physcomitrella patens, but there is no plant model yet to investigate U-to-C RNA editing. The hornwort Anthoceros agrestis is now emerging as such a model system. We report on the assembly and analyses of the A. agrestis chloroplast and mitochondrial genomes, their transcriptomes and editomes, and a large nuclear gene family encoding pentatricopeptide repeat (PPR) proteins likely acting as RNA editing factors. Both organelles in A. agrestis feature high amounts of RNA editing, with altogether > 1100 sites of C-to-U and 1300 sites of U-to-C editing. The nuclear genome reveals > 1400 genes for PPR proteins with variable carboxyterminal DYW domains. We observe significant variants of the 'classic' DYW domain, in the meantime confirmed as the cytidine deaminase for C-to-U editing, and discuss the first attractive candidates for reverse editing factors given their excellent matches to U-to-C editing targets according to the PPR-RNA binding code.
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Affiliation(s)
- Philipp Gerke
- Institut für Zelluläre und Molekulare Botanik (IZMB), University of Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstr. 107, 8008, Zürich, Switzerland
| | - Anna Neubauer
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstr. 107, 8008, Zürich, Switzerland
| | - Henning Lenz
- IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Bernard Gutmann
- EditForce Inc., West Zone #429, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan
| | - Rose McDowell
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia at Crawley, Perth, WA, 6009, Australia
| | - Ian Small
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia at Crawley, Perth, WA, 6009, Australia
| | | | - Volker Knoop
- Institut für Zelluläre und Molekulare Botanik (IZMB), University of Bonn, Kirschallee 1, 53115, Bonn, Germany
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9
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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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10
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Ngu M, Massel K, Bonen L. Group II introns in wheat mitochondria have degenerate structural features and varied splicing pathways. Int J Biochem Cell Biol 2017; 91:156-167. [PMID: 28495309 DOI: 10.1016/j.biocel.2017.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 04/28/2017] [Accepted: 05/06/2017] [Indexed: 11/29/2022]
Abstract
Mitochondrial introns in flowering plant genes are virtually all classified as members of the group II ribozyme family although certain structural features have degenerated to varying degrees over evolutionary time. We are interested in the impact that unconventional intron architecture might have on splicing biochemistry in vivo and we have focused in particular on intronic domains V and VI, which for self-splicing introns provide a key component of the catalytic core and the bulged branchpoint adenosine, respectively. Notably, the two transesterification steps in classical group II splicing are the same as for nuclear spliceosomal introns and release the intron as a lariat. Using RT-PCR and circularized RT-PCR, we had previously demonstrated that several wheat mitochondrial introns which lack a branchpoint adenosine have atypical splicing pathways, and we have now extended this analysis to the full set of wheat introns, namely six trans-splicing and sixteen cis-splicing ones. A number of introns are excised using non-lariat pathways and interestingly, we find that several introns which do have a conventional domain VI also use pathways that appear to exploit other internal or external nucleophiles, with the lariat form being relatively minor. Somewhat surprisingly, several introns with weakly-structured domain V/VI helices still exhibit classical lariat splicing, suggesting that accessory factors aid in restoring a splicing-competent conformation. Our observations illustrate that the loss of conventional group II features during evolution is correlated with altered splicing biochemistry in an intron-distinctive manner.
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Affiliation(s)
- Matthew Ngu
- Biology Department, University of Ottawa, Ottawa, K1N 6N5, Canada
| | - Karen Massel
- Biology Department, University of Ottawa, Ottawa, K1N 6N5, Canada
| | - Linda Bonen
- Biology Department, University of Ottawa, Ottawa, K1N 6N5, Canada.
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Donnelly K, Cottrell J, Ennos RA, Vendramin GG, A'Hara S, King S, Perry A, Wachowiak W, Cavers S. Reconstructing the plant mitochondrial genome for marker discovery: a case study using Pinus. Mol Ecol Resour 2017; 17:943-954. [DOI: 10.1111/1755-0998.12646] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/25/2016] [Accepted: 12/14/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Kevin Donnelly
- NERC Centre for Ecology and Hydrology, Edinburgh; Bush Estate Penicuik Midlothian EH26 0QB UK
- Institute of Evolutionary Biology; School of Biological Sciences; Ashworth Laboratories; University of Edinburgh; Edinburgh EH9 3JT UK
| | - Joan Cottrell
- Forest Research, Northern Research Station; Roslin Midlothian EH25 9SY UK
| | - Richard A. Ennos
- Institute of Evolutionary Biology; School of Biological Sciences; Ashworth Laboratories; University of Edinburgh; Edinburgh EH9 3JT UK
| | - Giovanni Giuseppe Vendramin
- Institute of Biosciences and BioResources; Division of Florence; National Research Council; Via Madonna del Piano, 10 50019 Sesto Fiorentino (Firenze) Italy
| | - Stuart A'Hara
- Forest Research, Northern Research Station; Roslin Midlothian EH25 9SY UK
| | - Sarah King
- NERC Centre for Ecology and Hydrology, Edinburgh; Bush Estate Penicuik Midlothian EH26 0QB UK
| | - Annika Perry
- NERC Centre for Ecology and Hydrology, Edinburgh; Bush Estate Penicuik Midlothian EH26 0QB UK
| | - Witold Wachowiak
- NERC Centre for Ecology and Hydrology, Edinburgh; Bush Estate Penicuik Midlothian EH26 0QB UK
- Institute of Dendrology; Polish Academy of Sciences; Parkowa 5 62-035 Kórnik Poland
| | - Stephen Cavers
- NERC Centre for Ecology and Hydrology, Edinburgh; Bush Estate Penicuik Midlothian EH26 0QB UK
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Guo W, Zhu A, Fan W, Mower JP. Complete mitochondrial genomes from the ferns Ophioglossum californicum and Psilotum nudum are highly repetitive with the largest organellar introns. THE NEW PHYTOLOGIST 2017; 213:391-403. [PMID: 27539928 DOI: 10.1111/nph.14135] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/06/2016] [Indexed: 05/07/2023]
Abstract
Currently, complete mitochondrial genomes (mitogenomes) are available from all major land plant lineages except ferns. Sequencing of fern mitogenomes could shed light on the major evolutionary transitions that established mitogenomic diversity among extant lineages. In this study, we generated complete mitogenomes from the adder's tongue fern (Ophioglossum californicum) and the whisk fern (Psilotum nudum). The Psilotum mitogenome (628 kb) contains a rich complement of genes and introns, some of which are the largest of any green plant organellar genome. In the Ophioglossum mitogenome (372 kb), gene and intron content is slightly reduced, including the loss of all four mitochondrial ccm genes. Transcripts of nuclear Ccm genes also were not detected, suggesting loss of the entire mitochondrial cytochrome c maturation pathway from Ophioglossum. Both fern mitogenomes are highly repetitive, yet they show extremely low levels of active recombination. Transcriptomic sequencing uncovered ˜1000 sites of C-to-U RNA editing in both species, plus a small number (< 60) of U-to-C edit sites. Overall, the first mitochondrial genomes of ferns show a mix of features shared with lycophytes and/or seed plants and several novel genomic features, enabling a robust reconstruction of the mitogenome in the common ancestor of vascular plants.
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Affiliation(s)
- Wenhu Guo
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, 68588, USA
- School of Biological Sciences, University of Nebraska, Lincoln, NE, 68588, USA
- ACGT Inc., Wheeling, IL, 60090, USA
| | - Andan Zhu
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, 68588, USA
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, 68583, USA
| | - Weishu Fan
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, 68588, USA
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, 68583, USA
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, 68588, USA
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, 68583, USA
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13
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Grewe F, Zhu A, Mower JP. Loss of a Trans-Splicing nad1 Intron from Geraniaceae and Transfer of the Maturase Gene matR to the Nucleus in Pelargonium. Genome Biol Evol 2016; 8:3193-3201. [PMID: 27664178 PMCID: PMC5174742 DOI: 10.1093/gbe/evw233] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial nad1 gene of seed plants has a complex structure, including four introns in cis or trans configurations and a maturase gene (matR) hosted within the final intron. In the geranium family (Geraniaceae), however, sequencing of representative species revealed that three of the four introns, including one in a trans configuration and another that hosts matR, were lost from the nad1 gene in their common ancestor. Despite the loss of the host intron, matR has been retained as a freestanding gene in most genera of the family, indicating that this maturase has additional functions beyond the splicing of its host intron. In the common ancestor of Pelargonium, matR was transferred to the nuclear genome, where it was split into two unlinked genes that encode either its reverse transcriptase or maturase domain. Both nuclear genes are transcribed and contain predicted mitochondrial targeting signals, suggesting that they express functional proteins that are imported into mitochondria. The nuclear localization and split domain structure of matR in the Pelargonium nuclear genome offers a unique opportunity to assess the function of these two domains using transgenic approaches.
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Affiliation(s)
- Felix Grewe
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska.,Integrative Research Center, The Field Museum of Natural History, Chicago, Illinois
| | - Andan Zhu
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska .,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska
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Analysis of the Complete Mitochondrial Genome Sequence of the Diploid Cotton Gossypium raimondii by Comparative Genomics Approaches. BIOMED RESEARCH INTERNATIONAL 2016; 2016:5040598. [PMID: 27847816 PMCID: PMC5099484 DOI: 10.1155/2016/5040598] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 09/26/2016] [Indexed: 11/17/2022]
Abstract
Cotton is one of the most important economic crops and the primary source of natural fiber and is an important protein source for animal feed. The complete nuclear and chloroplast (cp) genome sequences of G. raimondii are already available but not mitochondria. Here, we assembled the complete mitochondrial (mt) DNA sequence of G. raimondii into a circular genome of length of 676,078 bp and performed comparative analyses with other higher plants. The genome contains 39 protein-coding genes, 6 rRNA genes, and 25 tRNA genes. We also identified four larger repeats (63.9 kb, 10.6 kb, 9.1 kb, and 2.5 kb) in this mt genome, which may be active in intramolecular recombination in the evolution of cotton. Strikingly, nearly all of the G. raimondii mt genome has been transferred to nucleus on Chr1, and the transfer event must be very recent. Phylogenetic analysis reveals that G. raimondii, as a member of Malvaceae, is much closer to another cotton (G. barbadense) than other rosids, and the clade formed by two Gossypium species is sister to Brassicales. The G. raimondii mt genome may provide a crucial foundation for evolutionary analysis, molecular biology, and cytoplasmic male sterility in cotton and other higher plants.
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Knie N, Grewe F, Knoop V. Monilophyte mitochondrial rps1 genes carry a unique group II intron that likely originated from an ancient paralog in rpl2. RNA (NEW YORK, N.Y.) 2016; 22:1338-48. [PMID: 27354706 PMCID: PMC4986890 DOI: 10.1261/rna.056572.116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 05/19/2016] [Indexed: 05/10/2023]
Abstract
Intron patterns in plant mitochondrial genomes differ significantly between the major land plant clades. We here report on a new, clade-specific group II intron in the rps1 gene of monilophytes (ferns). This intron, rps1i25g2, is strikingly similar to rpl2i846g2 previously identified in the mitochondrial rpl2 gene of seed plants, ferns, and the lycophyte Phlegmariurus squarrosus Although mitochondrial ribosomal protein genes are frequently subject to endosymbiotic gene transfer among plants, we could retrieve the mitochondrial rps1 gene in a taxonomically wide sampling of 44 monilophyte taxa including basal lineages such as the Ophioglossales, Psilotales, and Marattiales with the only exception being the Equisetales (horsetails). Introns rps1i25g2 and rpl2i846g2 were likewise consistently present with only two exceptions: Intron rps1i25g2 is lost in the genus Ophioglossum and intron rpl2i846g2 is lost in Equisetum bogotense Both intron sequences are moderately affected by RNA editing. The unprecedented primary and secondary structure similarity of rps1i25g2 and rpl2i846g2 suggests an ancient retrotransposition event copying rpl2i846g2 into rps1, for which we suggest a model. Our phylogenetic analysis adding the new rps1 locus to a previous data set is fully congruent with recent insights on monilophyte phylogeny and further supports a sister relationship of Gleicheniales and Hymenophyllales.
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Affiliation(s)
- Nils Knie
- Abteilung Molekulare Evolution, IZMB-Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
| | - Felix Grewe
- Abteilung Molekulare Evolution, IZMB-Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
| | - Volker Knoop
- Abteilung Molekulare Evolution, IZMB-Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
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16
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Zumkeller SM, Knoop V, Knie N. Convergent Evolution of Fern-Specific Mitochondrial Group II Intron atp1i361g2 and Its Ancient Source Paralogue rps3i249g2 and Independent Losses of Intron and RNA Editing among Pteridaceae. Genome Biol Evol 2016; 8:2505-19. [PMID: 27492234 PMCID: PMC5010907 DOI: 10.1093/gbe/evw173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2016] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial intron patterns are highly divergent between the major land plant clades. An intron in the atp1 gene, atp1i361g2, is an example for a group II intron specific to monilophytes (ferns). Here, we report that atp1i361g2 is lost independently at least 4 times in the fern family Pteridaceae. Such plant organelle intron losses have previously been found to be accompanied by loss of RNA editing sites in the flanking exon regions as a consequence of genomic recombination of mature cDNA. Instead, we now observe that RNA editing events in both directions of pyrimidine exchange (C-to-U and U-to-C) are retained in atp1 exons after loss of the intron in Pteris argyraea/biaurita and in Actiniopteris and Onychium We find that atp1i361g2 has significant similarity with intron rps3i249g2 present in lycophytes and gymnosperms, which we now also find highly conserved in ferns. We conclude that atp1i361g2 may have originated from the more ancestral rps3i249g2 paralogue by a reverse splicing copy event early in the evolution of monilophytes. Secondary structure elements of the two introns, most characteristically their domains III, show strikingly convergent evolution in the monilophytes. Moreover, the intron paralogue rps3i249g2 reveals relaxed evolution in taxa where the atp1i361g2 paralogue is lost. Our findings may reflect convergent evolution of the two related mitochondrial introns exerted by co-evolution with an intron-binding protein simultaneously acting on the two paralogues.
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Affiliation(s)
- Simon Maria Zumkeller
- Abteilung Molekulare Evolution, IZMB-Institut Für Zelluläre Und Molekulare Botanik, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
| | - Volker Knoop
- Abteilung Molekulare Evolution, IZMB-Institut Für Zelluläre Und Molekulare Botanik, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
| | - Nils Knie
- Abteilung Molekulare Evolution, IZMB-Institut Für Zelluläre Und Molekulare Botanik, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
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17
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Jonathan Shaw A, Devos N, Liu Y, Cox CJ, Goffinet B, Flatberg KI, Shaw B. Organellar phylogenomics of an emerging model system: Sphagnum (peatmoss). ANNALS OF BOTANY 2016; 118:185-96. [PMID: 27268484 PMCID: PMC4970357 DOI: 10.1093/aob/mcw086] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/11/2016] [Accepted: 03/28/2016] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS Sphagnum-dominated peatlands contain approx. 30 % of the terrestrial carbon pool in the form of partially decomposed plant material (peat), and, as a consequence, Sphagnum is currently a focus of studies on biogeochemistry and control of global climate. Sphagnum species differ in ecologically important traits that scale up to impact ecosystem function, and sequencing of the genome from selected Sphagnum species is currently underway. As an emerging model system, these resources for Sphagnum will facilitate linking nucleotide variation to plant functional traits, and through those traits to ecosystem processes. A solid phylogenetic framework for Sphagnum is crucial to comparative analyses of species-specific traits, but relationships among major clades within Sphagnum have been recalcitrant to resolution because the genus underwent a rapid radiation. Herein a well-supported hypothesis for phylogenetic relationships among major clades within Sphagnum based on organellar genome sequences (plastid, mitochondrial) is provided. METHODS We obtained nucleotide sequences (273 753 nucleotides in total) from the two organellar genomes from 38 species (including three outgroups). Phylogenetic analyses were conducted using a variety of methods applied to nucleotide and amino acid sequences. The Sphagnum phylogeny was rooted with sequences from the related Sphagnopsida genera, Eosphagnum and Flatbergium KEY RESULTS Phylogenetic analyses of the data converge on the following subgeneric relationships: (Rigida (((Subsecunda) (Cuspidata)) ((Sphagnum) (Acutifolia))). All relationships were strongly supported. Species in the two major clades (i.e. Subsecunda + Cuspidata and Sphagnum + Acutifolia), which include >90 % of all Sphagnum species, differ in ecological niches and these differences correlate with other functional traits that impact biogeochemical cycling. Mitochondrial intron presence/absence are variable among species and genera of the Sphagnopsida. Two new nomenclatural combinations are made, in the genera Eosphagnum and Flatbergium CONCLUSIONS Newly resolved relationships now permit phylogenetic analyses of morphological, biochemical and ecological traits among Sphagnum species. The results clarify long-standing disagreements about subgeneric relationships and intrageneric classification.
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Affiliation(s)
- A Jonathan Shaw
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Nicolas Devos
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Yang Liu
- Department of Ecology and Evolutionary Biology, 75 North Eagleville Road, Storrs, CT 06269, USA
| | - Cymon J Cox
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, Edif. 7, 8005-139 Faro, Portugal
| | - Bernard Goffinet
- Department of Ecology and Evolutionary Biology, 75 North Eagleville Road, Storrs, CT 06269, USA
| | - Kjell Ivar Flatberg
- NTNU University Museum, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Blanka Shaw
- Department of Biology, Duke University, Durham, NC 27708, USA
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18
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Filyushin MA, Reshetnikova NM, Kochieva EZ, Skryabin KG. Polymorphism of sequences and the secondary structure of b/c intron of mitochondrial gene nad1 in Monotropa hypopitys and related ericaceae species. BIOL BULL+ 2016. [DOI: 10.1134/s1062359016030043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Multiple splicing pathways of group II trans-splicing introns in wheat mitochondria. Mitochondrion 2016; 28:23-32. [PMID: 26970277 DOI: 10.1016/j.mito.2016.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/06/2016] [Accepted: 03/08/2016] [Indexed: 11/23/2022]
Abstract
Trans-splicing of discontinuous introns in plant mitochondria requires the assembly of independently-transcribed precursor RNAs into splicing-competent structures, and they are expected to be excised as Y-branched molecules ("broken lariats") because these introns belong to the group II ribozyme family. We now demonstrate that this is just one of several trans-splicing pathways for wheat mitochondrial nad1 intron 4 and nad5 intron 2; they also use a hydrolytic pathway and the liberated 5'-half-intron linear molecules are unexpectedly abundant in the RNA population. We also observe a third productive splicing pathway for nad5 intron 2 that yields full-length excised introns in which the termini are joined in vivo and possess non-encoded nucleotides. In the case of trans-splicing nad1 intron 1, which has a weakly-structured and poorly-conserved core sequence, excision appears to be solely through a hydrolytic pathway. When wheat embryos are germinated in the cold rather than at room temperature, an increased complexity in trans-splicing products is seen for nad1 intron 4, suggesting that there can be environmental effects on the RNA folding of bipartite introns. Our observations provide insights into intron evolution and the complexity of RNA processing events in plant mitochondria.
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20
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Park S, Grewe F, Zhu A, Ruhlman TA, Sabir J, Mower JP, Jansen RK. Dynamic evolution of Geranium mitochondrial genomes through multiple horizontal and intracellular gene transfers. THE NEW PHYTOLOGIST 2015; 208:570-83. [PMID: 25989702 DOI: 10.1111/nph.13467] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 04/15/2015] [Indexed: 05/20/2023]
Abstract
The exchange of genetic material between cellular organelles through intracellular gene transfer (IGT) or between species by horizontal gene transfer (HGT) has played an important role in plant mitochondrial genome evolution. The mitochondrial genomes of Geraniaceae display a number of unusual phenomena including highly accelerated rates of synonymous substitutions, extensive gene loss and reduction in RNA editing. Mitochondrial DNA sequences assembled for 17 species of Geranium revealed substantial reduction in gene and intron content relative to the ancestor of the Geranium lineage. Comparative analyses of nuclear transcriptome data suggest that a number of these sequences have been functionally relocated to the nucleus via IGT. Evidence for rampant HGT was detected in several Geranium species containing foreign organellar DNA from diverse eudicots, including many transfers from parasitic plants. One lineage has experienced multiple, independent HGT episodes, many of which occurred within the past 5.5 Myr. Both duplicative and recapture HGT were documented in Geranium lineages. The mitochondrial genome of Geranium brycei contains at least four independent HGT tracts that are absent in its nearest relative. Furthermore, G. brycei mitochondria carry two copies of the cox1 gene that differ in intron content, providing insight into contrasting hypotheses on cox1 intron evolution.
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Affiliation(s)
- Seongjun Park
- Department of Integrative Biology, University of Texas, Austin, TX, 78712, USA
| | - Felix Grewe
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, 68588, USA
| | - Andan Zhu
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, 68588, USA
| | - Tracey A Ruhlman
- Department of Integrative Biology, University of Texas, Austin, TX, 78712, USA
| | - Jamal Sabir
- Department of Biological Science, Biotechnology Research Group, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Jeffrey P Mower
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, 68588, USA
| | - Robert K Jansen
- Department of Integrative Biology, University of Texas, Austin, TX, 78712, USA
- Department of Biological Science, Biotechnology Research Group, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
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Oldenkott B, Yamaguchi K, Tsuji-Tsukinoki S, Knie N, Knoop V. Chloroplast RNA editing going extreme: more than 3400 events of C-to-U editing in the chloroplast transcriptome of the lycophyte Selaginella uncinata. RNA (NEW YORK, N.Y.) 2014; 20:1499-506. [PMID: 25142065 PMCID: PMC4174432 DOI: 10.1261/rna.045575.114] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
RNA editing in chloroplasts and mitochondria of land plants differs significantly in abundance. For example, some 200-500 sites of cytidine-to-uridine RNA editing exist in flowering plant mitochondria as opposed to only 30-50 such C-to-U editing events in their chloroplasts. In contrast, we predicted significantly more chloroplast RNA editing for the protein-coding genes in the available complete plastome sequences of two species of the spike moss genus Selaginella (Lycopodiophyta). To evaluate these predictions we investigated the Selaginella uncinata chloroplast transcriptome. Our exhaustive cDNA studies identified the extraordinary number of 3415 RNA-editing events, exclusively of the C-to-U type, in the 74 mRNAs encoding intact reading frames in the S. uncinata chloroplast. We find the overwhelming majority (61%) of the 428 silent editing events leaving codon meanings unaltered directly neighboring other editing events, possibly suggesting a sterically more flexible RNA-editing deaminase activity in Selaginella. No evidence of RNA editing was found for tRNAs or rRNAs but we identified a total of 74 editing sites in cDNA sequences of four group II introns (petBi6g2, petDi8g2, ycf3i124g2, and ycf3i354g2) retained in partially matured transcripts, which strongly contribute to improved base-pairing in the intron secondary structures as a likely prerequisite for their splicing.
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Affiliation(s)
- Bastian Oldenkott
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Kazuo Yamaguchi
- Division of Functional Genomics, Advanced Science Research Center, Kanazawa University, Kanazawa 920-0934, Japan
| | - Sumika Tsuji-Tsukinoki
- Division of Functional Genomics, Advanced Science Research Center, Kanazawa University, Kanazawa 920-0934, Japan
| | - Nils Knie
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Volker Knoop
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
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22
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Park S, Ruhlman TA, Sabir JSM, Mutwakil MHZ, Baeshen MN, Sabir MJ, Baeshen NA, Jansen RK. Complete sequences of organelle genomes from the medicinal plant Rhazya stricta (Apocynaceae) and contrasting patterns of mitochondrial genome evolution across asterids. BMC Genomics 2014; 15:405. [PMID: 24884625 PMCID: PMC4045975 DOI: 10.1186/1471-2164-15-405] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 05/15/2014] [Indexed: 11/17/2022] Open
Abstract
Background Rhazya stricta is native to arid regions in South Asia and the Middle East and is used extensively in folk medicine to treat a wide range of diseases. In addition to generating genomic resources for this medicinally important plant, analyses of the complete plastid and mitochondrial genomes and a nuclear transcriptome from Rhazya provide insights into inter-compartmental transfers between genomes and the patterns of evolution among eight asterid mitochondrial genomes. Results The 154,841 bp plastid genome is highly conserved with gene content and order identical to the ancestral organization of angiosperms. The 548,608 bp mitochondrial genome exhibits a number of phenomena including the presence of recombinogenic repeats that generate a multipartite organization, transferred DNA from the plastid and nuclear genomes, and bidirectional DNA transfers between the mitochondrion and the nucleus. The mitochondrial genes sdh3 and rps14 have been transferred to the nucleus and have acquired targeting presequences. In the case of rps14, two copies are present in the nucleus; only one has a mitochondrial targeting presequence and may be functional. Phylogenetic analyses of both nuclear and mitochondrial copies of rps14 across angiosperms suggests Rhazya has experienced a single transfer of this gene to the nucleus, followed by a duplication event. Furthermore, the phylogenetic distribution of gene losses and the high level of sequence divergence in targeting presequences suggest multiple, independent transfers of both sdh3 and rps14 across asterids. Comparative analyses of mitochondrial genomes of eight sequenced asterids indicates a complicated evolutionary history in this large angiosperm clade with considerable diversity in genome organization and size, repeat, gene and intron content, and amount of foreign DNA from the plastid and nuclear genomes. Conclusions Organelle genomes of Rhazya stricta provide valuable information for improving the understanding of mitochondrial genome evolution among angiosperms. The genomic data have enabled a rigorous examination of the gene transfer events. Rhazya is unique among the eight sequenced asterids in the types of events that have shaped the evolution of its mitochondrial genome. Furthermore, the organelle genomes of R. stricta provide valuable genomic resources for utilizing this important medicinal plant in biotechnology applications. Electronic supplementary material The online version of this article (doi: 10.1186/1471-2164-15-405) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | - Robert K Jansen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
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23
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Cohen S, Zmudjak M, Colas des Francs-Small C, Malik S, Shaya F, Keren I, Belausov E, Many Y, Brown GG, Small I, Ostersetzer-Biran O. nMAT4, a maturase factor required for nad1 pre-mRNA processing and maturation, is essential for holocomplex I biogenesis in Arabidopsis mitochondria. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:253-68. [PMID: 24506473 DOI: 10.1111/tpj.12466] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/17/2014] [Accepted: 01/28/2014] [Indexed: 05/23/2023]
Abstract
Group II introns are large catalytic RNAs that are found in bacteria and organellar genomes of lower eukaryotes, but are particularly prevalent within mitochondria in plants, where they are present in many critical genes. The excision of plant mitochondrial introns is essential for respiratory functions, and is facilitated in vivo by various protein cofactors. Typical group II introns are classified as mobile genetic elements, consisting of the self-splicing ribozyme and its own intron-encoded maturase protein. A hallmark of maturases is that they are intron-specific, acting as cofactors that bind their intron-containing pre-RNAs to facilitate splicing. However, the degeneracy of the mitochondrial introns in plants and the absence of cognate intron-encoded maturase open reading frames suggest that their splicing in vivo is assisted by 'trans'-acting protein factors. Interestingly, angiosperms harbor several nuclear-encoded maturase-related (nMat) genes that contain N-terminal mitochondrial localization signals. Recently, we established the roles of two of these paralogs in Arabidopsis, nMAT1 and nMAT2, in the splicing of mitochondrial introns. Here we show that nMAT4 (At1g74350) is required for RNA processing and maturation of nad1 introns 1, 3 and 4 in Arabidopsis mitochondria. Seed germination, seedling establishment and development are strongly affected in homozygous nmat4 mutants, which also show modified respiration phenotypes that are tightly associated with complex I defects.
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Affiliation(s)
- Sigal Cohen
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat-Ram, Jerusalem, 91904, Israel
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Dalby SJ, Bonen L. Impact of low temperature on splicing of atypical group II introns in wheat mitochondria. Mitochondrion 2013; 13:647-55. [PMID: 24056090 DOI: 10.1016/j.mito.2013.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/14/2013] [Accepted: 09/06/2013] [Indexed: 12/31/2022]
Abstract
To investigate the impact of cold on group II intron splicing, we compared the physical forms of excised mitochondrial introns from wheat embryos germinated at room temperature and 4°C. For introns which deviate from the conventional branchpoint structure, we observed predominantly heterogeneous circularized introns in the cold rather than linear polyadenylated forms arising from a hydrolytic pathway as seen at room temperature. In addition, intron-containing precursors are elevated relative to mature mRNAs upon cold treatment. Our findings indicate that low temperature growth not only reduces splicing efficiency, but also shifts the splicing biochemistry of atypical group II introns to novel, yet productive, pathways.
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Affiliation(s)
- Stephen J Dalby
- Biology Department, University of Ottawa, Ottawa K1N 6N5, Canada
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Guo W, Mower JP. Evolution of Plant Mitochondrial Intron-Encoded Maturases: Frequent Lineage-Specific Loss and Recurrent Intracellular Transfer to the Nucleus. J Mol Evol 2013; 77:43-54. [DOI: 10.1007/s00239-013-9579-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/12/2013] [Indexed: 12/24/2022]
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Graham L, Lewis LA, Taylor W, Wellman C, Cook M. Early Terrestrialization: Transition from Algal to Bryophyte Grade. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/978-94-007-6988-5_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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27
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Grewe F, Guo W, Gubbels EA, Hansen AK, Mower JP. Complete plastid genomes from Ophioglossum californicum, Psilotum nudum, and Equisetum hyemale reveal an ancestral land plant genome structure and resolve the position of Equisetales among monilophytes. BMC Evol Biol 2013; 13:8. [PMID: 23311954 PMCID: PMC3553075 DOI: 10.1186/1471-2148-13-8] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 01/07/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Plastid genome structure and content is remarkably conserved in land plants. This widespread conservation has facilitated taxon-rich phylogenetic analyses that have resolved organismal relationships among many land plant groups. However, the relationships among major fern lineages, especially the placement of Equisetales, remain enigmatic. RESULTS In order to understand the evolution of plastid genomes and to establish phylogenetic relationships among ferns, we sequenced the plastid genomes from three early diverging species: Equisetum hyemale (Equisetales), Ophioglossum californicum (Ophioglossales), and Psilotum nudum (Psilotales). A comparison of fern plastid genomes showed that some lineages have retained inverted repeat (IR) boundaries originating from the common ancestor of land plants, while other lineages have experienced multiple IR changes including expansions and inversions. Genome content has remained stable throughout ferns, except for a few lineage-specific losses of genes and introns. Notably, the losses of the rps16 gene and the rps12i346 intron are shared among Psilotales, Ophioglossales, and Equisetales, while the gain of a mitochondrial atp1 intron is shared between Marattiales and Polypodiopsida. These genomic structural changes support the placement of Equisetales as sister to Ophioglossales + Psilotales and Marattiales as sister to Polypodiopsida. This result is augmented by some molecular phylogenetic analyses that recover the same relationships, whereas others suggest a relationship between Equisetales and Polypodiopsida. CONCLUSIONS Although molecular analyses were inconsistent with respect to the position of Marattiales and Equisetales, several genomic structural changes have for the first time provided a clear placement of these lineages within the ferns. These results further demonstrate the power of using rare genomic structural changes in cases where molecular data fail to provide strong phylogenetic resolution.
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Affiliation(s)
- Felix Grewe
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, USA
| | - Wenhu Guo
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA
- School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
| | - Emily A Gubbels
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA
- School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
| | - A Katie Hansen
- School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
- Present address: College of Natural Sciences, The University of Texas at Austin, Austin, TX, USA
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, USA
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Cooper ED, Henwood MJ, Brown EA. Are the liverworts really that old? Cretaceous origins and Cenozoic diversifications in Lepidoziaceae reflect a recurrent theme in liverwort evolution. Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01946.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Murray J. Henwood
- Heydon-Laurence Building A08; University of Sydney; School of Biological Sciences; Sydney; NSW 2006; Australia
| | - Elizabeth A. Brown
- National Herbarium of New South Wales; Mrs Macquaries Road; Sydney; NSW 2000; Australia
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Hepburn NJ, Schmidt DW, Mower JP. Loss of two introns from the Magnolia tripetala mitochondrial cox2 gene implicates horizontal gene transfer and gene conversion as a novel mechanism of intron loss. Mol Biol Evol 2012; 29:3111-20. [PMID: 22593225 DOI: 10.1093/molbev/mss130] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Intron loss is often thought to occur through retroprocessing, which is the reverse transcription and genomic integration of a spliced transcript. In plant mitochondria, several unambiguous examples of retroprocessing are supported by the parallel loss of an intron and numerous adjacent RNA edit sites, but in most cases, the evidence for intron loss via retroprocessing is weak or lacking entirely. To evaluate mechanisms of intron loss, we designed a polymerase chain reaction (PCR)-based assay to detect recent intron losses from the mitochondrial cox2 gene within genus Magnolia, which was previously suggested to have variability in cox2 intron content. Our assay showed that all 22 examined species have a cox2 gene with two introns. However, one species, Magnolia tripetala, contains an additional cox2 gene that lacks both introns. Quantitative PCR showed that both M. tripetala cox2 genes are present in the mitochondrial genome. Although the intronless gene has lost several ancestral RNA edit sites, their distribution is inconsistent with retroprocessing models. Instead, phylogenetic and gene conversion analyses indicate that the intronless gene was horizontally acquired from a eudicot and then underwent gene conversion with the native intron-containing gene. The models are presented to summarize the roles of horizontal gene transfer and gene conversion as a novel mechanism of intron loss.
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Affiliation(s)
- Nancy J Hepburn
- Center for Plant Science Innovation, University of Nebraska, NE, USA
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30
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Liu Y, Wang B, Cui P, Li L, Xue JY, Yu J, Qiu YL. The mitochondrial genome of the lycophyte Huperzia squarrosa: the most archaic form in vascular plants. PLoS One 2012; 7:e35168. [PMID: 22511984 PMCID: PMC3325193 DOI: 10.1371/journal.pone.0035168] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Accepted: 03/13/2012] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial genomes have maintained some bacterial features despite their residence within eukaryotic cells for approximately two billion years. One of these features is the frequent presence of polycistronic operons. In land plants, however, it has been shown that all sequenced vascular plant chondromes lack large polycistronic operons while bryophyte chondromes have many of them. In this study, we provide the completely sequenced mitochondrial genome of a lycophyte, from Huperzia squarrosa, which is a member of the sister group to all other vascular plants. The genome, at a size of 413,530 base pairs, contains 66 genes and 32 group II introns. In addition, it has 69 pseudogene fragments for 24 of the 40 protein- and rRNA-coding genes. It represents the most archaic form of mitochondrial genomes of all vascular plants. In particular, it has one large conserved gene cluster containing up to 10 ribosomal protein genes, which likely represents a polycistronic operon but has been disrupted and greatly reduced in the chondromes of other vascular plants. It also has the least rearranged gene order in comparison to the chondromes of other vascular plants. The genome is ancestral in vascular plants in several other aspects: the gene content resembling those of charophytes and most bryophytes, all introns being cis-spliced, a low level of RNA editing, and lack of foreign DNA of chloroplast or nuclear origin.
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Affiliation(s)
- Yang Liu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bin Wang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Peng Cui
- CAS Key Laboratory of Genome Science and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Libo Li
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jia-Yu Xue
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- School of Life Sciences, Nanjing University, Nanjing, Jiangsu, People's Republic of China
| | - Jun Yu
- CAS Key Laboratory of Genome Science and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Yin-Long Qiu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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31
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Cuenca A, Petersen G, Seberg O, Jahren AH. Genes and processed paralogs co-exist in plant mitochondria. J Mol Evol 2012; 74:158-69. [PMID: 22484699 DOI: 10.1007/s00239-012-9496-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 03/23/2012] [Indexed: 10/28/2022]
Abstract
RNA-mediated gene duplication has been proposed to create processed paralogs in the plant mitochondrial genome. A processed paralog may retain signatures left by the maturation process of its RNA precursor, such as intron removal and no need of RNA editing. Whereas it is well documented that an RNA intermediary is involved in the transfer of mitochondrial genes to the nucleus, no direct evidence exists for insertion of processed paralogs in the mitochondria (i.e., processed and un-processed genes have never been found simultaneously in the mitochondrial genome). In this study, we sequenced a region of the mitochondrial gene nad1, and identified a number of taxa were two different copies of the region co-occur in the mitochondria. The two nad1 paralogs differed in their (a) presence or absence of a group II intron, and (b) number of edited sites. Thus, this work provides the first evidence of co-existence of processed paralogs and their precursors within the plant mitochondrial genome. In addition, mapping the presence/absence of the paralogs provides indirect evidence of RNA-mediated gene duplication as an essential process shaping the mitochondrial genome in plants.
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Affiliation(s)
- Argelia Cuenca
- Botanical Garden, Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83 Opg. S, 1307, Copenhagen K, Denmark.
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Nadimi M, Beaudet D, Forget L, Hijri M, Lang BF. Group I intron-mediated trans-splicing in mitochondria of Gigaspora rosea and a robust phylogenetic affiliation of arbuscular mycorrhizal fungi with Mortierellales. Mol Biol Evol 2012; 29:2199-210. [PMID: 22411852 DOI: 10.1093/molbev/mss088] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gigaspora rosea is a member of the arbuscular mycorrhizal fungi (AMF; Glomeromycota) and a distant relative of Glomus species that are beneficial to plant growth. To allow for a better understanding of Glomeromycota, we have sequenced the mitochondrial DNA of G. rosea. A comparison with Glomus mitochondrial genomes reveals that Glomeromycota undergo insertion and loss of mitochondrial plasmid-related sequences and exhibit considerable variation in introns. The gene order between the two species is almost completely reshuffled. Furthermore, Gigaspora has fragmented cox1 and rns genes, and an unorthodox initiator tRNA that is tailored to decoding frequent UUG initiation codons. For the fragmented cox1 gene, we provide evidence that its RNA is joined via group I-mediated trans-splicing, whereas rns RNA remains in pieces. According to our model, the two cox1 precursor RNA pieces are brought together by flanking cox1 exon sequences that form a group I intron structure, potentially in conjunction with the nad5 intron 3 sequence. Finally, we present analyses that address the controversial phylogenetic association of Glomeromycota within fungi. According to our results, Glomeromycota are not a separate group of paraphyletic zygomycetes but branch together with Mortierellales, potentially also Harpellales.
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Affiliation(s)
- Maryam Nadimi
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
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Volkmar U, Groth-Malonek M, Heinrichs J, Muhle H, Polsakiewicz M, Knoop V. Exclusive conservation of mitochondrial group II intron nad4i548 among liverworts and its use for phylogenetic studies in this ancient plant clade. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:382-391. [PMID: 21973214 DOI: 10.1111/j.1438-8677.2011.00499.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Liverworts occupy a pivotal position in land plant (embryophyte) phylogeny as the presumed earliest-branching major clade, sister to all other land plants, including the mosses, hornworts, lycophytes, monilophytes and seed plants. Molecular support for this earliest dichotomy in land plant phylogeny comes from strikingly different occurrences of introns in mitochondrial genes distinguishing liverworts from all other embryophytes. Exceptionally, however, the nad5 gene--the mitochondrial locus hitherto used most widely to elucidate early land plant phylogeny--carries a group I type intron that is shared between liverworts and mosses. We here explored whether a group II intron, the other major type of organellar intron, would similarly be conserved in position across the entire diversity of extant liverworts and could be of use for phylogenetic analyses in this supposedly most ancient embryophyte clade. To this end, we investigated the nad4 gene as a candidate locus possibly featuring different introns in liverworts as opposed to the non-liverwort embryophyte (NLE) lineage. We indeed found group II intron nad4i548 universally conserved in a wide phylogenetic sampling of 55 liverwort taxa, confirming clade specificity and surprising evolutionary stability of plant mitochondrial introns. As expected, intron nad4i548g2 carries phylogenetic information in its variable sequences, which confirms and extends previous cladistic insights on liverwort evolution. We integrate the new nad4 data with those of the previously established mitochondrial nad5 and the chloroplast rbcL and rps4 genes and present a phylogeny based on the fused datasets. Notably, the phylogenetic analyses suggest a reconsideration of previous phylogenetic and taxonomic assignments for the genera Calycularia and Mylia and resolve a sister group relationship of Ptilidiales and Porellales.
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Affiliation(s)
- U Volkmar
- Institut für Zelluläre und Molekulare Botanik, Abt Molekulare Evolution, Universität Bonn, Bonn, Germany
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Zhang T, Fang Y, Wang X, Deng X, Zhang X, Hu S, Yu J. The complete chloroplast and mitochondrial genome sequences of Boea hygrometrica: insights into the evolution of plant organellar genomes. PLoS One 2012; 7:e30531. [PMID: 22291979 PMCID: PMC3264610 DOI: 10.1371/journal.pone.0030531] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 12/23/2011] [Indexed: 11/26/2022] Open
Abstract
The complete nucleotide sequences of the chloroplast (cp) and mitochondrial (mt) genomes of resurrection plant Boea hygrometrica (Bh, Gesneriaceae) have been determined with the lengths of 153,493 bp and 510,519 bp, respectively. The smaller chloroplast genome contains more genes (147) with a 72% coding sequence, and the larger mitochondrial genome have less genes (65) with a coding faction of 12%. Similar to other seed plants, the Bh cp genome has a typical quadripartite organization with a conserved gene in each region. The Bh mt genome has three recombinant sequence repeats of 222 bp, 843 bp, and 1474 bp in length, which divide the genome into a single master circle (MC) and four isomeric molecules. Compared to other angiosperms, one remarkable feature of the Bh mt genome is the frequent transfer of genetic material from the cp genome during recent Bh evolution. We also analyzed organellar genome evolution in general regarding genome features as well as compositional dynamics of sequence and gene structure/organization, providing clues for the understanding of the evolution of organellar genomes in plants. The cp-derived sequences including tRNAs found in angiosperm mt genomes support the conclusion that frequent gene transfer events may have begun early in the land plant lineage.
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Affiliation(s)
- Tongwu Zhang
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, China
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Yongjun Fang
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, China
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Xumin Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Xin Deng
- CAS Key Laboratory of Photosynthesis and Molecular Physiology, Research Center of Plant Molecular and Development Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Xiaowei Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
- * E-mail: (XZ); (SH); (JY)
| | - Songnian Hu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
- * E-mail: (XZ); (SH); (JY)
| | - Jun Yu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
- * E-mail: (XZ); (SH); (JY)
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35
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Seed Plant Mitochondrial Genomes: Complexity Evolving. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2012. [DOI: 10.1007/978-94-007-2920-9_8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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36
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Liu Y, Xue JY, Wang B, Li L, Qiu YL. The mitochondrial genomes of the early land plants Treubia lacunosa and Anomodon rugelii: dynamic and conservative evolution. PLoS One 2011; 6:e25836. [PMID: 21998706 PMCID: PMC3187804 DOI: 10.1371/journal.pone.0025836] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 09/12/2011] [Indexed: 11/19/2022] Open
Abstract
Early land plant mitochondrial genomes captured important changes of mitochondrial genome evolution when plants colonized land. The chondromes of seed plants show several derived characteristics, e.g., large genome size variation, rapid intra-genomic rearrangement, abundant introns, and highly variable levels of RNA editing. On the other hand, the chondromes of charophytic algae are still largely ancestral in these aspects, resembling those of early eukaryotes. When the transition happened has been a long-standing question in studies of mitochondrial genome evolution. Here we report complete mitochondrial genome sequences from an early-diverging liverwort, Treubia lacunosa, and a late-evolving moss, Anomodon rugelii. The two genomes, 151,983 and 104,239 base pairs in size respectively, contain standard sets of protein coding genes for respiration and protein synthesis, as well as nearly full sets of rRNA and tRNA genes found in the chondromes of the liverworts Marchantia polymorpha and Pleurozia purpurea and the moss Physcomitrella patens. The gene orders of these two chondromes are identical to those of the other liverworts and moss. Their intron contents, with all cis-spliced group I or group II introns, are also similar to those in the previously sequenced liverwort and moss chondromes. These five chondromes plus the two from the hornworts Phaeoceros laevis and Megaceros aenigmaticus for the first time allowed comprehensive comparative analyses of structure and organization of mitochondrial genomes both within and across the three major lineages of bryophytes. These analyses led to the conclusion that the mitochondrial genome experienced dynamic evolution in genome size, gene content, intron acquisition, gene order, and RNA editing during the origins of land plants and their major clades. However, evolution of this organellar genome has remained rather conservative since the origin and initial radiation of early land plants, except within vascular plants.
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Affiliation(s)
- Yang Liu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jia-Yu Xue
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- School of Life Sciences, Nanjing University, Nanjing, Jiangsu, People’s Republic of China
| | - Bin Wang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Libo Li
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Yin-Long Qiu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
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37
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He XM, Ji N, Xiang XC, Luo P, Bao JK. Purification, characterization, and molecular cloning of a novel antifungal lectin from the roots of Ophioglossum pedunculosum. Appl Biochem Biotechnol 2011; 165:1458-72. [PMID: 21947760 DOI: 10.1007/s12010-011-9367-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 09/01/2011] [Indexed: 10/17/2022]
Abstract
A novel mannan-specific lectin was isolated from the roots of a traditional Chinese herbal medicine, Ophioglossum pedunculosum through ion-exchange chromatography and gel filtration. With a molecular mass of 19,835.7 Da demonstrated by MALDI-TOF analysis, this novel agglutinin was designated as O. pedunculosum agglutinin (OPA), specifically agglutinating human O erythrocytes and rabbit erythrocytes. The hemagglutination could be strongly inhibited by mannan and thyroglobulin, the activity of which was stable in pH range of 4.0-8.0 and at temperatures below 50 °C. Chemical modification studies indicated that tryptophan and arginine residues were essential for its hemagglutinating activity. Meanwhile, it showed antifungal activities toward Sclerotium rolfsii and Fusarium graminearum. In addition, to amplify cDNA of OPA by 3'/5'-rapid amplification of cDNA ends (RACE), the N-terminal 30 amino acids sequence of OPA was determined, and degenerate primers were designed. The obtained full-length cDNA of OPA contained 885 bp with an open-reading frame of 600 bp encoding a precursor protein of 199 amino acids, while the mature protein had 170 amino acids.
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Affiliation(s)
- Xue-Mei He
- School of Life Sciences, Sichuan University, Chengdu 610064, China
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Bégu D, Castandet B, Araya A. RNA editing restores critical domains of a group I intron in fern mitochondria. Curr Genet 2011; 57:317-25. [DOI: 10.1007/s00294-011-0349-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/07/2011] [Accepted: 06/10/2011] [Indexed: 11/28/2022]
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Hecht J, Grewe F, Knoop V. Extreme RNA editing in coding islands and abundant microsatellites in repeat sequences of Selaginella moellendorffii mitochondria: the root of frequent plant mtDNA recombination in early tracheophytes. Genome Biol Evol 2011; 3:344-58. [PMID: 21436122 PMCID: PMC5654404 DOI: 10.1093/gbe/evr027] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Using an independent fosmid cloning approach and comprehensive transcriptome analysis to complement data from the Selaginella moellendorffii genome project, we determined the complete mitochondrial genome structure of this spikemoss. Numerous recombination events mediated mainly via long sequence repeats extending up to 7kbp result in a complex mtDNA network structure. Peculiar features associated with the repeat sequences are more than 80 different microsatellite sites (predominantly trinucleotide motifs). The S. moellendorffii mtDNA encodes a plant-typical core set of a twin-arginine translocase (tatC), 17 respiratory chain subunits, and 2 rRNAs but lacks atp4 and any tRNA genes. As a further novelty among plant chondromes, the nad4L gene is encoded within an intron of the nad1 gene. A total of 37 introns occupying the 20 mitochondrial genes (four of which are disrupted into trans-splicing arrangements including two novel instances of trans-splicing introns) make the S. moellendorffii chondrome the intron-richest and gene-poorest plant mtDNA known. Our parallel transcriptome analyses demonstrates functional splicing of all 37 introns and reveals a new record amount of plant organelle RNA editing with a total of 2,139 sites in mRNAs and 13 sites in the two rRNAs, all of which are exclusively of the C-to-U type.
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Affiliation(s)
- Julia Hecht
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
| | - Felix Grewe
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
| | - Volker Knoop
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
- Corresponding author: E-mail:
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40
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Cooper ED, Shaw AJ, Shaw B, Henwood MJ, Heslewood MM, Brown EA. A multi-locus molecular phylogeny of the Lepidoziaceae: laying the foundations for a stable classification. Mol Phylogenet Evol 2011; 59:489-509. [PMID: 21316477 DOI: 10.1016/j.ympev.2011.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/31/2011] [Accepted: 02/02/2011] [Indexed: 11/29/2022]
Abstract
The Lepidoziaceae, with over 700 species in 30 genera, is one of the largest leafy liverwort families. Despite receiving considerable attention, the composition of subfamilies and genera remains unsatisfactorily resolved. In this study, 10 loci (one nuclear 26S, two mitochondrial nad1 and rps3, and seven chloroplast atpB, psbA, psbT-psbH, rbcL, rps4, trnG and trnL-trnF) are used to estimate the phylogeny of 93 species of Lepidoziaceae. These molecular data provide strong evidence against the monophyly of three subfamilies; Lepidozioideae, Lembidioideae and Zoopsidoideae, and seven of the 20 sampled genera; Lepidozia, Telaranea, Kurzia, Zoopsis, Lembidium, Paracromastigum and Chloranthelia. Several robust clades are recognised that might provide the basis for a revised subfamily circumscription including a narrower circumscription of the Lepidozioideae and a more inclusive Lembidioideae. Neogrollea notabilis is returned to the Lepidoziaceae and Megalembidium insulanum is placed in the Lembidioideae.
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Affiliation(s)
- Endymion D Cooper
- School of Biological Sciences, University of Sydney, NSW 2006, Australia.
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41
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Increased accumulation of intron-containing transcripts in rice mitochondria caused by low temperature: is cold-sensitive RNA editing implicated? Curr Genet 2010; 56:529-41. [DOI: 10.1007/s00294-010-0320-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 09/01/2010] [Accepted: 09/07/2010] [Indexed: 12/20/2022]
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42
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Regina TMR, Quagliariello C. Lineage-specific group II intron gains and losses of the mitochondrial rps3 gene in gymnosperms. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2010; 48:646-54. [PMID: 20605476 DOI: 10.1016/j.plaphy.2010.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 04/26/2010] [Accepted: 05/04/2010] [Indexed: 05/04/2023]
Abstract
According to PCR assays and sequencing, we now report the shared presence of two rps3 introns, namely the rps3i74 and the rps3i249, in the mitochondria of all the classes representing the surviving lineages of gymnosperms, and unveil several lineages experiencing intron loss. Interestingly, the rps3 intron gains and losses within the four groups of gymnosperms let us sort out the Pinaceae and the non-Pinaceae into intron (+)- and intron (-)-lineages, respectively. Worthy of mention is also the finding that only Gnetum within the Gnetales harbours both the rps3 introns. This intron distribution pattern is consistent with the hypothesis that the two rps3 introns were likely present in the common ancestor of the seed plants and, then, independently lost in the non-Pinaceae during gymnosperm evolution. The derived secondary structural model of the novel group IIA intron improves our understanding of the significance and origin of the extraordinary length polymorphisms observed among rps3i249 orthologs. Despite the remarkable structural plasticity to adopt and reject introns, the rps3 mRNAs undergo accurate processing by splicing and extensive editing in gymnosperm mitochondria. This study provides additional insights into the evolutionarily high dynamics of mitochondrial introns which may come and go in closely related plant species. The turnover of the mitochondrial rps3 group II introns seen among lineages of seed plants further suggests that these introns might be an additional signature to discriminate between particularly cryptical taxonomic groups for which there is a need of a further evaluation of their evolutionary affiliation.
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Affiliation(s)
- Teresa M R Regina
- Dipartimento di Biologia Cellulare, Università degli Studi della Calabria, Ponte P. Bucci, 87030 Arcavacata di Rende, Italy
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43
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Volkmar U, Knoop V. Introducing intron locus cox1i624 for phylogenetic analyses in Bryophytes: on the issue of Takakia as sister genus to all other extant mosses. J Mol Evol 2010; 70:506-18. [PMID: 20473660 DOI: 10.1007/s00239-010-9348-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 04/13/2010] [Indexed: 11/30/2022]
Abstract
Liverworts are well supported as the sister group to all other land plants (embryophytes) by molecular data. Observations strongly supporting this earliest dichotomy in embryophyte evolution are the strikingly different introns occurring in the mitochondrial DNAs of liverworts versus non-liverwort embryophytes (NLE), including the mosses. A final conclusion on the most basal lineages of mosses, for which genera such as Sphagnum and Takakia are the most likely candidates, is lacking. We have now investigated cox1i624, a mitochondrial group I intron conserved between the moss Physcomitrella patens and the liverwort Marchantia polymorpha. Focusing on a sampling of liverwort and moss genera, which had previously been identified as early branching taxa in their respective clades, we find that group I intron cox1i624 is universally conserved in all 33 mosses and 11 liverworts investigated. The group I intron core secondary structure is well conserved between the two ancient land plant clades. However, whereas dramatic size reductions are seen in the moss phylogeny, exactly the opposite is observed for liverworts. The cox1i624g1 locus was used for phylogenetic tree reconstruction also in combination with data sets of nad5i753g1 as well as chloroplast loci rbcL and rps4. The phylogenetic analyses revealed (i) very good support for the Treubiopsida as sister clade to all other liverworts, (ii) a sister group relationship of the nematodontous Tetraphidopsida and Polytrichopsida and (iii) two rivalling hypotheses about the basal-most moss genus with mitochondrial loci suggesting an isolated Takakia as sister to all other mosses and chloroplast loci indicating a Takakia-Sphagnum clade.
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Affiliation(s)
- Ute Volkmar
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abt. Molekulare Evolution, Universität Bonn, Kirschallee 1, Bonn, Germany.
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44
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Hata S, Kobae Y, Banba M. Interactions Between Plants and Arbuscular Mycorrhizal Fungi. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 281:1-48. [DOI: 10.1016/s1937-6448(10)81001-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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45
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Xue JY, Liu Y, Li L, Wang B, Qiu YL. The complete mitochondrial genome sequence of the hornwort Phaeoceros laevis: retention of many ancient pseudogenes and conservative evolution of mitochondrial genomes in hornworts. Curr Genet 2009; 56:53-61. [DOI: 10.1007/s00294-009-0279-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 11/19/2009] [Accepted: 11/21/2009] [Indexed: 10/20/2022]
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46
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Elina H, Brown GG. Extensive mis-splicing of a bi-partite plant mitochondrial group II intron. Nucleic Acids Res 2009; 38:996-1008. [PMID: 19920126 PMCID: PMC2817487 DOI: 10.1093/nar/gkp994] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Expression of the seed plant mitochondrial nad5 gene involves two trans-splicing events that remove fragmented group II introns and join the small, central exon c to exons b and d. We show that in both monocot and eudicot plants, extensive mis-splicing of the bi-partite intron 2 takes place, resulting in the formation of aberrantly spliced products in which exon c is joined to various sites within exon b. These mis-spliced products accumulate to levels comparable to or greater than that of the correctly spliced mRNA. We suggest that mis-splicing may result from folding constraints imposed on intron 2 by base-pairing between exon a and a portion of the bi-partite intron 3 downstream of exon c. Consistent with this hypothesis, we find that mis-splicing does not occur in Oenothera mitochondria, where intron 3 is further fragmented such that the predicted base-pairing region is not covalently linked to exon c. Our findings suggest that intron fragmentation may lead to mis-splicing, which may be corrected by further intron fragmentation.
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Affiliation(s)
- Helen Elina
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada
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47
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Wang B, Xue J, Li L, Liu Y, Qiu YL. The complete mitochondrial genome sequence of the liverwort Pleurozia purpurea reveals extremely conservative mitochondrial genome evolution in liverworts. Curr Genet 2009; 55:601-9. [PMID: 19756627 DOI: 10.1007/s00294-009-0273-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 08/27/2009] [Accepted: 08/29/2009] [Indexed: 11/29/2022]
Abstract
Plant mitochondrial genomes have been known to be highly unusual in their large sizes, frequent intra-genomic rearrangement, and generally conservative sequence evolution. Recent studies show that in early land plants the mitochondrial genomes exhibit a mixed mode of conservative yet dynamic evolution. Here, we report the completely sequenced mitochondrial genome from the liverwort Pleurozia purpurea. The circular genome has a size of 168,526 base pairs, containing 43 protein-coding genes, 3 rRNA genes, 25 tRNA genes, and 31 group I or II introns. It differs from the Marchantia polymorpha mitochondrial genome, the only other liverwort chondriome that has been sequenced, in lacking two genes (trnRucg and trnTggu) and one intron (rrn18i1065gII). The two genomes have identical gene orders and highly similar sequences in exons, introns, and intergenic spacers. Finally, a comparative analysis of duplicated trnRucu and other trnR genes from the two liverworts and several other organisms identified the recent lateral origin of trnRucg in Marchantia mtDNA through modification of a duplicated trnRucu. This study shows that the mitochondrial genomes evolve extremely slowly in liverworts, the earliest-diverging lineage of extant land plants, in stark contrast to what is known of highly dynamic evolution of mitochondrial genomes in seed plants.
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Affiliation(s)
- Bin Wang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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48
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Grewe F, Viehoever P, Weisshaar B, Knoop V. A trans-splicing group I intron and tRNA-hyperediting in the mitochondrial genome of the lycophyte Isoetes engelmannii. Nucleic Acids Res 2009; 37:5093-104. [PMID: 19553190 PMCID: PMC2731911 DOI: 10.1093/nar/gkp532] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 06/05/2009] [Accepted: 06/06/2009] [Indexed: 11/27/2022] Open
Abstract
Plant mitochondrial genomes show much more evolutionary plasticity than those of animals. We analysed the first mitochondrial DNA (mtDNA) of a lycophyte, the quillwort Isoetes engelmannii, which is separated from seed plants by more than 350 million years of evolution. The Isoetes mtDNA is particularly rich in recombination events, and chloroplast as well as nuclear DNA inserts document the incorporation of foreign sequences already in this most ancestral vascular plant lineage. On the other hand, particularly small group II introns and short intergenic regions reveal a tendency of evolution towards a compact mitochondrial genome. RNA editing reaches extreme levels exceeding 100 pyrimidine exchanges in individual mRNAs and, hitherto unobserved in such frequency, also in tRNAs with 18 C-to-U conversions in the tRNA for proline. In total, some 1500 sites of RNA editing can be expected for the Isoetes mitochondrial transcriptome. As a unique molecular novelty, the Isoetes cox1 gene requires trans-splicing via a discontinuous group I intron demonstrating disrupted, but functional, RNAs for yet another class of natural ribozymes.
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Affiliation(s)
- Felix Grewe
- Institut für Zelluläre und Molekulare Botanik (IZMB), Universität Bonn, Kirschallee 1, 53115 Bonn and Institut für Genomforschung und Systembiologie (IGS), Universität Bielefeld, Universitätsstraße 25, 33594 Bielefeld, Germany
| | - Prisca Viehoever
- Institut für Zelluläre und Molekulare Botanik (IZMB), Universität Bonn, Kirschallee 1, 53115 Bonn and Institut für Genomforschung und Systembiologie (IGS), Universität Bielefeld, Universitätsstraße 25, 33594 Bielefeld, Germany
| | - Bernd Weisshaar
- Institut für Zelluläre und Molekulare Botanik (IZMB), Universität Bonn, Kirschallee 1, 53115 Bonn and Institut für Genomforschung und Systembiologie (IGS), Universität Bielefeld, Universitätsstraße 25, 33594 Bielefeld, Germany
| | - Volker Knoop
- Institut für Zelluläre und Molekulare Botanik (IZMB), Universität Bonn, Kirschallee 1, 53115 Bonn and Institut für Genomforschung und Systembiologie (IGS), Universität Bielefeld, Universitätsstraße 25, 33594 Bielefeld, Germany
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49
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The complete mitochondrial genome sequence of the hornwort Megaceros aenigmaticus shows a mixed mode of conservative yet dynamic evolution in early land plant mitochondrial genomes. J Mol Evol 2009; 68:665-78. [PMID: 19475442 DOI: 10.1007/s00239-009-9240-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 04/03/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
Abstract
Land plants possess some of the most unusual mitochondrial genomes among eukaryotes. However, in early land plants these genomes resemble those of green and red algae or early eukaryotes. The question of when during land plant evolution the dramatic change in mtDNAs occurred remains unanswered. Here we report the first completely sequenced mitochondrial genome of the hornwort, Megaceros aenigmaticus, a member of the sister group of vascular plants. It is a circular molecule of 184,908 base pairs, with 32 protein genes, 3 rRNA genes, 17 tRNA genes, and 30 group II introns. The genome contains many genes arranged in the same order as in those of a liverwort, a moss, several green and red algae, and Reclinomonas americana, an early-branching eukaryote with the most ancestral form of mtDNA. In particular, the gene order between mtDNAs of the hornwort and Physcomitrella patens (moss) differs by only 8 inversions and translocations. However, the hornwort mtDNA possesses 4 derived features relative to green alga mtDNAs--increased genome size, RNA editing, intron gains, and gene losses--which were all likely acquired during the origin and early evolution of land plants. Overall, this genome and those of other 2 bryophytes show that mitochondrial genomes in early land plants, unlike their seed plant counterparts, exhibit a mixed mode of conservative yet dynamic evolution.
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50
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RNA editing: only eleven sites are present in the Physcomitrella patens mitochondrial transcriptome and a universal nomenclature proposal. Mol Genet Genomics 2009; 281:473-81. [PMID: 19169711 DOI: 10.1007/s00438-009-0424-z] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 01/05/2009] [Indexed: 10/21/2022]
Abstract
RNA editing in mitochondria and chloroplasts of land plants alters the coding content of transcripts through site-specific exchanges of cytidines into uridines and vice versa. The abundance of RNA editing in model plant species such as rice or Arabidopsis with some 500 affected sites in their organelle transcripts hinders straightforward approaches to elucidate its mechanisms. The moss Physcomitrella patens is increasingly being appreciated as an alternative plant model system, enhanced by the recent availability of its complete chloroplast, mitochondrial, and nuclear genome sequences. We here report the transcriptomic analysis of Physcomitrella mitochondrial mRNAs as a prerequisite for future studies of mitochondrial RNA editing in this moss. We find a strikingly low frequency of RNA editing affecting only eleven, albeit highly important, sites of C-to-U nucleotide modification in only nine mitochondrial genes. Partial editing was seen for two of these sites but no evidence for any silent editing sites (leaving the identity of the encoded amino acid unchanged) as commonly observed in vascular plants was found in Physcomitrella, indicating a compact and efficient organization of the editing machinery. Furthermore, we here wish to propose a unifying nomenclature to clearly identify and designate RNA editing positions and to facilitate future communication and database annotation.
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