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Lee C, Ruhlman TA, Jansen RK. Rate accelerations in plastid and mitochondrial genomes of Cyperaceae occur in the same clades. Mol Phylogenet Evol 2023; 182:107760. [PMID: 36921696 DOI: 10.1016/j.ympev.2023.107760] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 01/28/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023]
Abstract
Cyperaceae, the second largest family in the monocot order Poales, comprises >5500 species and includes the genus Eleocharis with ∼ 250 species. A previous study of complete plastomes of two Eleocharis species documented extensive structural heteroplasmy, gene order changes, high frequency of dispersed repeats along with gene losses and duplications. To better understand the phylogenetic distribution of gene and intron content as well as rates and patterns of sequence evolution within and between mitochondrial and plastid genomes of Eleocharis and Cyperaceae, an additional 29 Eleocharis organelle genomes were sequenced and analyzed. Eleocharis experienced extensive gene loss in both genomes while loss of introns was mitochondria-specific. Eleocharis has higher rates of synonymous (dS) and nonsynonymous (dN) substitutions in the plastid and mitochondrion than most sampled angiosperms, and the pattern was distinct from other eudicot lineages with accelerated rates. Several clades showed higher dS and dN in mitochondrial genes than in plastid genes. Furthermore, nucleotide substitution rates of mitochondrial genes were significantly accelerated on the branch leading to Cyperaceae compared to most angiosperms. Mitochondrial genes of Cyperaceae exhibited dramatic loss of RNA editing sites and a negative correlation between RNA editing and dS values was detected among angiosperms. Mutagenic retroprocessing and dysfunction of DNA replication, repair and recombination genes are the most likely cause of striking rate accelerations and loss of edit sites and introns in Eleocharis and Cyperaceae organelle genomes.
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Affiliation(s)
- Chaehee Lee
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA.
| | - Tracey A Ruhlman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Robert K Jansen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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2
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Kraft LJ, Sit TL, Diepenbrock LM, Ashrafi H, Aryal R, Fernandez GE, Burrack HJ. Detection of Fruit Meals Within Laboratory-Raised and Field-Trapped Adult Drosophila suzukii (Diptera: Drosophilidae) Guts. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.719645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The feeding habits of adult Brachycera are understudied and may provide important context for understanding invasive pest biology, as with the polyphagous small fruit pest Drosophila suzukii. We developed molecular methods to study adult D. suzukii gut content in order to understand its feeding habits. We designed and verified two primer pairs specific for either blueberries or blackberries and used a qPCR melt curve analysis to determine whether we can detect the presence or absence of berry feeding by adult flies. In a laboratory assay, the blueberry fly meal DNA can be detected for longer periods than the blackberry meal DNA. Generally, female gut contents are less variable than male gut contents. We also tested recently emerged flies that were not fed as adults but developed as larvae in either blueberries or blackberries. Some adult flies from each fruit had detectable fruit DNA in their gut, which could be due to pupal meconium feeding after emergence. Next, we aimed to test the primers in the field to develop techniques to track fruit feeding by D. suzukii in its natural field environment. First, to identify the most appropriate collection method, we determined how long we could detect fruit DNA, using previously developed primers within D. suzukii gut preserved in four types of trap fluid in the laboratory. The likelihood of detecting blackberry DNA differed by day, trap fluid, and between sexes. For the blueberry primer, the possibility of detecting blueberry DNA differed by trap fluid only. Based on those results, we used RV antifreeze with a Scentry SWD lure in field trials at two research station locations, one containing blackberries and one with blueberries. We established transects away from each fruit planting and collected up to 120 total flies at each point along transects. There were no significant differences in the number of flies containing berry DNA among collection points along the transect in both locations. These results suggest that adult flies move between crop and non-crop habitats and may not be highly dependent on fruit food resources.
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Kim JI, Jeong M, Archibald JM, Shin W. Comparative Plastid Genomics of Non-Photosynthetic Chrysophytes: Genome Reduction and Compaction. FRONTIERS IN PLANT SCIENCE 2020; 11:572703. [PMID: 33013997 PMCID: PMC7511666 DOI: 10.3389/fpls.2020.572703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/24/2020] [Indexed: 05/11/2023]
Abstract
Spumella-like heterotrophic chrysophytes are important eukaryotic microorganisms that feed on bacteria in aquatic and soil environments. They are characterized by their lack of pigmentation, naked cell surface, and extremely small size. Although Spumella-like chrysophytes have lost their photosynthetic ability, they still possess a leucoplast and retain a plastid genome. We have sequenced the plastid genomes of three non-photosynthetic chrysophytes, Spumella sp. Baeckdong012018B8, Pedospumella sp. Jangsampo120217C5 and Poteriospumella lacustris Yongseonkyo072317C3, and compared them to the previously sequenced plastid genome of "Spumella" sp. NIES-1846 and photosynthetic chrysophytes. We found the plastid genomes of Spumella-like flagellates to be generally conserved with respect to genome structure and housekeeping gene content. We nevertheless also observed lineage-specific gene rearrangements and duplication of partial gene fragments at the boundary of the inverted repeat and single copy regions. Most gene losses correspond to genes for proteins involved in photosynthesis and carbon fixation, except in the case of petF. The newly sequenced plastid genomes range from ~55.7 kbp to ~62.9 kbp in size and share a core set of 45 protein-coding genes, 3 rRNAs, and 32 to 34 tRNAs. Our results provide insight into the evolutionary history of organelle genomes via genome reduction and gene loss related to loss of photosynthesis in chrysophyte evolution.
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Affiliation(s)
- Jong Im Kim
- Department of Biology, Chungnam National University, Daejeon, South Korea
| | - Minseok Jeong
- Department of Biology, Chungnam National University, Daejeon, South Korea
| | - John M. Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Woongghi Shin
- Department of Biology, Chungnam National University, Daejeon, South Korea
- *Correspondence: Woongghi Shin,
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Zhang W, Zhao Y, Yang G, Peng J, Chen S, Xu Z. Determination of the evolutionary pressure on Camellia oleifera on Hainan Island using the complete chloroplast genome sequence. PeerJ 2019; 7:e7210. [PMID: 31289703 PMCID: PMC6599451 DOI: 10.7717/peerj.7210] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 05/26/2019] [Indexed: 01/08/2023] Open
Abstract
Camellia oleifera is one of the four largest woody edible oil plants in the world with high ecological and medicinal values. Due to frequent interspecific hybridization, it was difficult to study its genetics and evolutionary history. This study used C. oleifera that was collected on Hainan Island to conduct our research. The unique island environment makes the quality of tea oil higher than that of other species grown in the mainland. Moreover, a long-term geographic isolation might affect gene structure. In order to better understand the molecular biology of this species, protect excellent germplasm resources, and promote the population genetics and phylogenetic studies of Camellia plants, high-throughput sequencing technology was used to obtain the chloroplast genome sequence of Hainan C. oleifera. The results showed that the whole chloroplast genome of C. oleifera in Hainan was 156,995 bp in length, with a typical quadripartite structure of a large single copy (LSC) region of 86,648 bp, a small single copy (SSC) region of 18,297 bp, and a pair of inverted repeats (IRs) of 26,025 bp. The whole genome encoded a total of 141 genes (115 different genes), including 88 protein-coding genes, 45 tRNA genes, and eight rRNA genes. Among these genes, nine genes contained one intron, two genes contained two introns, and four overlapping genes were also detected. The total GC content of Hainan C. oleifera's chloroplast genome was 37.29%. The chloroplast genome structure characteristics of Hainan C. oleifera were compared with mainland C. oleifera and those of the other eight closely related Theaceae species; it was found that the contractions and expansions of the IR/LSC and IR/SSC regions affected the length of chloroplast genome. The chloroplast genome sequences of these Theaceae species were highly similar. A comparative analysis indicated that the Theaceae species were conserved in structure and evolution. A total of 51 simple sequence repeat (SSR) loci were detected in the chloroplast genome of Hainan C. oleifera, and all Camellia plants did not have pentanucleotide repeats, which could be used as a good marker in phylogenetic studies. We also detected seven long repeats, the base composition of all repeats was biased toward A/T, which was consistent with the codon bias. It was found that Hainan C. oleifera had a similar evolutionary relationship with C. crapnelliana, through the use of codons and phylogenetic analysis. This study can provide an effective genomic resource for the evolutionary history of Theaceae family.
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Affiliation(s)
- Wan Zhang
- Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, Changsha, Hunan, China
| | - Yunlin Zhao
- Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, Changsha, Hunan, China
| | - Guiyan Yang
- Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, Changsha, Hunan, China
- College of Forestry, Northwest A & F University, Yangling, China
| | - Jiao Peng
- Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, Changsha, Hunan, China
| | - Shuwen Chen
- College of Forestry, Northwest A & F University, Yangling, China
| | - Zhenggang Xu
- Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, Changsha, Hunan, China
- Hunan Urban and Rural Ecological Planning and Restoration Engineering Research Center, Hunan City University, Yiyang, Hunan, China
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Karnkowska A, Bennett MS, Triemer RE. Dynamic evolution of inverted repeats in Euglenophyta plastid genomes. Sci Rep 2018; 8:16071. [PMID: 30375469 PMCID: PMC6207741 DOI: 10.1038/s41598-018-34457-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 10/18/2018] [Indexed: 11/22/2022] Open
Abstract
Photosynthetic euglenids (Euglenophyta) are a monophyletic group of unicellular eukaryotes characterized by the presence of plastids, which arose as the result of the secondary endosymbiosis. Many Euglenophyta plastid (pt) genomes have been characterized recently, but they represented mainly one family - Euglenaceae. Here, we report a comparative analysis of plastid genomes from eight representatives of the family Phacaceae. Newly sequenced plastid genomes share a number of features including synteny and gene content, except for genes mat2 and mat5 encoding maturases. The observed diversity of intron number and presence/absence of maturases corroborated previously suggested correlation between the number of maturases in the pt genome and intron proliferation. Surprisingly, pt genomes of taxa belonging to Discoplastis and Lepocinclis encode two inverted repeat (IR) regions containing the rDNA operon, which are absent from the Euglenaceae. By mapping the presence/absence of IR region on the obtained phylogenomic tree, we reconstructed the most probable events in the evolution of IRs in the Euglenophyta. Our study highlights the dynamic nature of the Euglenophyta plastid genome, in particular with regards to the IR regions that underwent losses repeatedly.
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Affiliation(s)
- Anna Karnkowska
- Department of Molecular Phylogenetics and Evolution, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, ul. Żwirki i Wigury 101, 02-089, Warsaw, Poland.
| | - Matthew S Bennett
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, Room# 166 Plant Biology Labs, East Lansing, Michigan, 48824, USA
| | - Richard E Triemer
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, Room# 166 Plant Biology Labs, East Lansing, Michigan, 48824, USA
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Muñoz-Gómez SA, Mejía-Franco FG, Durnin K, Colp M, Grisdale CJ, Archibald JM, Slamovits CH. The New Red Algal Subphylum Proteorhodophytina Comprises the Largest and Most Divergent Plastid Genomes Known. Curr Biol 2017; 27:1677-1684.e4. [DOI: 10.1016/j.cub.2017.04.054] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/24/2017] [Accepted: 04/26/2017] [Indexed: 12/25/2022]
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7
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Kamikawa R, Tanifuji G, Kawachi M, Miyashita H, Hashimoto T, Inagaki Y. Plastid genome-based phylogeny pinpointed the origin of the green-colored plastid in the dinoflagellate Lepidodinium chlorophorum. Genome Biol Evol 2015; 7:1133-40. [PMID: 25840416 PMCID: PMC4419806 DOI: 10.1093/gbe/evv060] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Unlike many other photosynthetic dinoflagellates, whose plastids contain a characteristic carotenoid peridinin, members of the genus Lepidodinium are the only known dinoflagellate species possessing green alga-derived plastids. However, the precise origin of Lepidodinium plastids has hitherto remained uncertain. In this study, we completely sequenced the plastid genome of Lepidodinium chlorophorum NIES-1868. Our phylogenetic analyses of 52 plastid-encoded proteins unite L. chlorophorum exclusively with a pedinophyte, Pedinomonas minor, indicating that the green-colored plastids in Lepidodinium spp. were derived from an endosymbiotic pedinophyte or a green alga closely related to pedinophytes. Our genome comparison incorporating the origin of the Lepidodinium plastids strongly suggests that the endosymbiont plastid genome acquired by the ancestral Lepidodinium species has lost genes encoding proteins involved in metabolism and biosynthesis, protein/metabolite transport, and plastid division during the endosymbiosis. We further discuss the commonalities and idiosyncrasies in genome evolution between the L. chlorophorum plastid and other plastids acquired through endosymbiosis of eukaryotic photoautotrophs.
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Affiliation(s)
- Ryoma Kamikawa
- Graduate School of Global Environmental Studies and Graduate School of Human and Environmental Studies, Kyoto University, Japan
| | - Goro Tanifuji
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Masanobu Kawachi
- The National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
| | - Hideaki Miyashita
- Graduate School of Global Environmental Studies and Graduate School of Human and Environmental Studies, Kyoto University, Japan
| | - Tetsuo Hashimoto
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan Center for Computational Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yuji Inagaki
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan Center for Computational Sciences, University of Tsukuba, Ibaraki, Japan
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8
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Coelho SM, Simon N, Ahmed S, Cock JM, Partensky F. Ecological and evolutionary genomics of marine photosynthetic organisms. Mol Ecol 2012; 22:867-907. [PMID: 22989289 DOI: 10.1111/mec.12000] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 07/10/2012] [Accepted: 07/15/2012] [Indexed: 01/05/2023]
Abstract
Environmental (ecological) genomics aims to understand the genetic basis of relationships between organisms and their abiotic and biotic environments. It is a rapidly progressing field of research largely due to recent advances in the speed and volume of genomic data being produced by next generation sequencing (NGS) technologies. Building on information generated by NGS-based approaches, functional genomic methodologies are being applied to identify and characterize genes and gene systems of both environmental and evolutionary relevance. Marine photosynthetic organisms (MPOs) were poorly represented amongst the early genomic models, but this situation is changing rapidly. Here we provide an overview of the recent advances in the application of ecological genomic approaches to both prokaryotic and eukaryotic MPOs. We describe how these approaches are being used to explore the biology and ecology of marine cyanobacteria and algae, particularly with regard to their functions in a broad range of marine ecosystems. Specifically, we review the ecological and evolutionary insights gained from whole genome and transcriptome sequencing projects applied to MPOs and illustrate how their genomes are yielding information on the specific features of these organisms.
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Affiliation(s)
- Susana M Coelho
- UPMC-Université Paris 06, Station Biologique de Roscoff, Roscoff, France.
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9
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Dorrell RG, Howe CJ. What makes a chloroplast? Reconstructing the establishment of photosynthetic symbioses. J Cell Sci 2012; 125:1865-75. [PMID: 22547565 DOI: 10.1242/jcs.102285] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Earth is populated by an extraordinary diversity of photosynthetic eukaryotes. Many eukaryotic lineages contain chloroplasts, obtained through the endosymbiosis of a wide range of photosynthetic prokaryotes or eukaryotes, and a wide variety of otherwise non-photosynthetic species form transient associations with photosynthetic symbionts. Chloroplast lineages are likely to be derived from pre-existing transient symbioses, but it is as yet poorly understood what steps are required for the establishment of permanent chloroplasts from photosynthetic symbionts. In the past decade, several species that contain relatively recently acquired chloroplasts, such as the rhizarian Paulinella chromatophora, and non-photosynthetic taxa that maintain photosynthetic symbionts, such as the sacoglossan sea slug Elysia, the ciliate Myrionecta rubra and the dinoflagellate Dinophysis, have emerged as potential model organisms in the study of chloroplast establishment. In this Commentary, we compare recent molecular insights into the maintenance of chloroplasts and photosynthetic symbionts from these lineages, and others that might represent the early stages of chloroplast establishment. We emphasise the importance in the establishment of chloroplasts of gene transfer events that minimise oxidative stress acting on the symbiont. We conclude by assessing whether chloroplast establishment is facilitated in some lineages by a mosaic of genes, derived from multiple symbiotic associations, encoded in the host nucleus.
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Affiliation(s)
- Richard G Dorrell
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
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Sloan DB, Alverson AJ, Wu M, Palmer JD, Taylor DR. Recent acceleration of plastid sequence and structural evolution coincides with extreme mitochondrial divergence in the angiosperm genus Silene. Genome Biol Evol 2012; 4:294-306. [PMID: 22247429 PMCID: PMC3318436 DOI: 10.1093/gbe/evs006] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The angiosperm genus Silene exhibits some of the most extreme and rapid divergence ever identified in mitochondrial genome architecture and nucleotide substitution rates. These patterns have been considered mitochondrial specific based on the absence of correlated changes in the small number of available nuclear and plastid gene sequences. To better assess the relationship between mitochondrial and plastid evolution, we sequenced the plastid genomes from four Silene species with fully sequenced mitochondrial genomes. We found that two species with fast-evolving mitochondrial genomes, S. noctiflora and S. conica, also exhibit accelerated rates of sequence and structural evolution in their plastid genomes. The nature of these changes, however, is markedly different from those in the mitochondrial genome. For example, in contrast to the mitochondrial pattern, which appears to be genome wide and mutationally driven, the plastid substitution rate accelerations are restricted to a subset of genes and preferentially affect nonsynonymous sites, indicating that altered selection pressures are acting on specific plastid-encoded functions in these species. Indeed, some plastid genes in S. noctiflora and S. conica show strong evidence of positive selection. In contrast, two species with more slowly evolving mitochondrial genomes, S. latifolia and S. vulgaris, have correspondingly low rates of nucleotide substitution in plastid genes as well as a plastid genome structure that has remained essentially unchanged since the origin of angiosperms. These results raise the possibility that common evolutionary forces could be shaping the extreme but distinct patterns of divergence in both organelle genomes within this genus.
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11
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Töpel M, Jarvis P. The Tic20 gene family: phylogenetic analysis and evolutionary considerations. PLANT SIGNALING & BEHAVIOR 2011; 6:1046-8. [PMID: 21633193 PMCID: PMC3257792 DOI: 10.4161/psb.6.7.15631] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 03/27/2011] [Indexed: 05/04/2023]
Abstract
Tic20 is a polytopic protein of the inner envelope membrane of chloroplasts, and it is proposed to act as a translocation channel during chloroplast protein import. By analysing 29 sequences from diverse organisms, it was evident that Tic20-related proteins form two distinct clades, termed Group 1 and Group 2. The former group includes canonical Tic20 proteins that are essential for chloroplast development, while members of the latter are of unknown function. An increased evolutionary rate, in connection with adaptation to terrestrial life, was detected in Group 1. Interestingly, the sub-cellular (genomic) localization of genes coding for Group 1 proteins differs between evolutionary lineages.
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Affiliation(s)
- Mats Töpel
- Department of Plant and Environmental Sciences; Göteborg University; Göteborg, Sweden
| | - Paul Jarvis
- Department of Biology; University of Leicester; Leicester, UK
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Iida S, Kobiyama A, Ogata T, Murakami A. Differential DNA rearrangements of plastid genes, psbA and psbD, in two species of the dinoflagellate Alexandrium. PLANT & CELL PHYSIOLOGY 2010; 51:1869-1877. [PMID: 20937609 DOI: 10.1093/pcp/pcq152] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Plastomes of the peridinin-containing dinoflagellates are composed of a limited number of genes, which are carried individually on small circular molecules, termed 'minicircles'. Although the prevalent plastid chromosome of most algae and plants has only a single copy of each gene, our previous study showed that low copy numbers of multiple variants of the gene psbA co-exist with the 'ordinary' gene encoding the D1 protein in minicircles of Alexandrium tamarense. Although none of the psbA variants encoded the entire protein, they persisted in culture. In this study, we compared the distribution and structure of psbA and psbD variants in two species of Alexandrium to characterize DNA rearrangement within these genes. In addition to four previously reported psbA variants, three psbD variants were found in A. tamarense minicircles. The ordinary psbA and psbD genes also co-existed with variants in another species, A. catenella. The sequences of the ordinary genes were virtually identical in the two species. All the variants comprised insertion or deletion mutations, with no base substitutions being identified. Duplicated parts of the coding sequences were contained in most of the insertions. Short direct repeats (4-14 bp) and/or adenine + thymine-rich motifs were present in all mutation regions, although the position and/or the sequence of each DNA rearrangement was unique to each variant. The results indicated that replication-based repeat-mediated recombination was responsible for generation of the variants.
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Affiliation(s)
- Satoko Iida
- Kobe University Research Center for Inland Seas, 2746 Iwaya, Awaji, 656-2401 Japan
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Donaher N, Tanifuji G, Onodera NT, Malfatti SA, Chain PSG, Hara Y, Archibald JM. The complete plastid genome sequence of the secondarily nonphotosynthetic alga Cryptomonas paramecium: reduction, compaction, and accelerated evolutionary rate. Genome Biol Evol 2009; 1:439-48. [PMID: 20333213 PMCID: PMC2839278 DOI: 10.1093/gbe/evp047] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2009] [Indexed: 12/23/2022] Open
Abstract
The cryptomonads are a group of unicellular algae that acquired photosynthesis through the engulfment of a red algal cell, a process called secondary endosymbiosis. Here, we present the complete plastid genome sequence of the secondarily nonphotosynthetic species Cryptomonas paramecium CCAP977/2a. The ∼78 kilobase pair (Kbp) C. paramecium genome contains 82 predicted protein genes, 29 transfer RNA genes, and a single pseudogene (atpF). The C. paramecium plastid genome is approximately 50 Kbp smaller than those of the photosynthetic cryptomonads Guillardia theta and Rhodomonas salina; 71 genes present in the G. theta and/or R. salina plastid genomes are missing in C. paramecium. The pet, psa, and psb photosynthetic gene families are almost entirely absent. Interestingly, the ribosomal RNA operon, present as inverted repeats in most plastid genomes (including G. theta and R. salina), exists as a single copy in C. paramecium. The G + C content (38%) is higher in C. paramecium than in other cryptomonad plastid genomes, and C. paramecium plastid genes are characterized by significantly different codon usage patterns and increased evolutionary rates. The content and structure of the C. paramecium plastid genome provides insight into the changes associated with recent loss of photosynthesis in a predominantly photosynthetic group of algae and reveals features shared with the plastid genomes of other secondarily nonphotosynthetic eukaryotes.
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Affiliation(s)
- Natalie Donaher
- Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
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