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Burk RD, Mirabello L, DeSalle R. Distinguishing Genetic Drift from Selection in Papillomavirus Evolution. Viruses 2023; 15:1631. [PMID: 37631973 PMCID: PMC10458755 DOI: 10.3390/v15081631] [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: 06/27/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023] Open
Abstract
Pervasive purifying selection on non-synonymous substitutions is a hallmark of papillomavirus genome history, but the role of selection on and the drift of non-coding DNA motifs on HPV diversification is poorly understood. In this study, more than a thousand complete genomes representing Alphapapillomavirus types, lineages, and SNP variants were examined phylogenetically and interrogated for the number and position of non-coding DNA sequence motifs using Principal Components Analyses, Ancestral State Reconstructions, and Phylogenetic Independent Contrasts. For anciently diverged Alphapapillomavirus types, composition of the four nucleotides (A, C, G, T), codon usage, trimer usage, and 13 established non-coding DNA sequence motifs revealed phylogenetic clusters consistent with genetic drift. Ancestral state reconstruction and Phylogenetic Independent Contrasts revealed ancient genome alterations, particularly for the CpG and APOBEC3 motifs. Each evolutionary analytical method we performed supports the unanticipated conclusion that genetic drift and different evolutionary drivers have structured Alphapapillomavirus genomes in distinct ways during successive epochs, even extending to differences in more recently formed variant lineages.
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Affiliation(s)
- Robert D. Burk
- Departments of Pediatrics, Microbiology & Immunology, Epidemiology & Population Health, Obstetrics, Gynecology and Woman’s Health, and Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lisa Mirabello
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Robert DeSalle
- Sackler Institute of Comparative Genomics, American Museum of Natural History, New York, NY 10024, USA
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2
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Iqbal WA, Lisitsa A, Kapralov MV. Predicting plant Rubisco kinetics from RbcL sequence data using machine learning. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:638-650. [PMID: 36094849 PMCID: PMC9833099 DOI: 10.1093/jxb/erac368] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 09/12/2022] [Indexed: 06/15/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is responsible for the conversion of atmospheric CO2 to organic carbon during photosynthesis, and often acts as a rate limiting step in the later process. Screening the natural diversity of Rubisco kinetics is the main strategy used to find better Rubisco enzymes for crop engineering efforts. Here, we demonstrate the use of Gaussian processes (GPs), a family of Bayesian models, coupled with protein encoding schemes, for predicting Rubisco kinetics from Rubisco large subunit (RbcL) sequence data. GPs trained on published experimentally obtained Rubisco kinetic datasets were applied to over 9000 sequences encoding RbcL to predict Rubisco kinetic parameters. Notably, our predicted kinetic values were in agreement with known trends, e.g. higher carboxylation turnover rates (Kcat) for Rubisco enzymes from C4 or crassulacean acid metabolism (CAM) species, compared with those found in C3 species. This is the first study demonstrating machine learning approaches as a tool for screening and predicting Rubisco kinetics, which could be applied to other enzymes.
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Affiliation(s)
- Wasim A Iqbal
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Alexei Lisitsa
- Department of Computer Science, University of Liverpool, Liverpool, L69 3BX, United Kingdom
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3
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Zecca G, Panzeri D, Grassi F. Detecting signals of adaptive evolution in grape plastomes with a focus on the Cretaceous-Palaeogene (K/Pg) transition. ANNALS OF BOTANY 2022; 130:965-980. [PMID: 36282948 PMCID: PMC9851337 DOI: 10.1093/aob/mcac128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 10/22/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND AND AIMS Although plastid genes are widely used in phylogenetic studies, signals of positive selection have been scarcely investigated in the grape family. The plastomes from 91 accessions of Vitaceae were examined to understand the extent to which positive selection is present and to identify which genes are involved. Moreover, the changes through time of genes under episodic positive selection were investigated and the hypothesis of an adaptive process following the Cretaceous-Palaeogene (K/Pg) transition about 66 million years ago was tested. METHODS Different codon-substitution models were used to assess pervasive and episodic positive selection events on 70 candidate plastid genes. Divergence times between lineages were estimated and stochastic character mapping analysis was used to simulate variation over time of the genes found to be under episodic positive selection. KEY RESULTS A total of 20 plastid genes (29 %) showed positive selection. Among them, 14 genes showed pervasive signatures of positive selection and nine genes showed episodic signatures of positive selection. In particular, four of the nine genes (psbK, rpl20, rpoB, rps11) exhibited a similar pattern showing an increase in the rate of variation close to the K/Pg transition. CONCLUSION Multiple analyses have shown that the grape family has experienced ancient and recent positive selection events and that the targeted genes are involved in essential functions such as photosynthesis, self-replication and metabolism. Our results are consistent with the idea that the K/Pg transition has favoured an increased rate of change in some genes. Intense environmental perturbations have influenced the rapid diversification of certain lineages, and new mutations arising on some plastid genes may have been fixed by natural selection over the course of many generations.
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Affiliation(s)
- Giovanni Zecca
- University of Milan-Bicocca, Department of Biotechnology and Bioscience, Piazza della Scienza 2, 20126, Milano, Italy
| | - Davide Panzeri
- University of Milan-Bicocca, Department of Biotechnology and Bioscience, Piazza della Scienza 2, 20126, Milano, Italy
| | - Fabrizio Grassi
- University of Milan-Bicocca, Department of Biotechnology and Bioscience, Piazza della Scienza 2, 20126, Milano, Italy
- NBFC, National Biodiversity Future Center, Palermo 90133, Italy
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4
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Xiao TW, Ge XJ. Plastome structure, phylogenomics, and divergence times of tribe Cinnamomeae (Lauraceae). BMC Genomics 2022; 23:642. [PMID: 36076185 PMCID: PMC9461114 DOI: 10.1186/s12864-022-08855-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/26/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tribe Cinnamomeae is a species-rich and ecologically important group in tropical and subtropical forests. Previous studies explored its phylogenetic relationships and historical biogeography using limited loci, which might result in biased molecular dating due to insufficient parsimony-informative sites. Thus, 15 plastomes were newly sequenced and combined with published plastomes to study plastome structural variations, gene evolution, phylogenetic relationships, and divergence times of this tribe. RESULTS Among the 15 newly generated plastomes, 14 ranged from 152,551 bp to 152,847 bp, and the remaining one (Cinnamomum chartophyllum XTBGLQM0164) was 158,657 bp. The inverted repeat (IR) regions of XTBGLQM0164 contained complete ycf2, trnICAU, rpl32, and rpl2. Four hypervariable plastid loci (ycf1, ycf2, ndhF-rpl32-trnLUAG, and petA-psbJ) were identified as candidate DNA barcodes. Divergence times based on a few loci were primarily determined by prior age constraints rather than by DNA data. In contrast, molecular dating using complete plastid protein-coding genes (PCGs) was determined by DNA data rather than by prior age constraints. Dating analyses using PCGs showed that Cinnamomum sect. Camphora diverged from C. sect. Cinnamomum in the late Oligocene (27.47 Ma). CONCLUSIONS This study reports the first case of drastic IR expansion in tribe Cinnamomeae, and indicates that plastomes have sufficient parsimony-informative sites for molecular dating. Besides, the dating analyses provide preliminary insights into the divergence time within tribe Cinnamomeae and can facilitate future studies on its historical biogeography.
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Affiliation(s)
- Tian-Wen Xiao
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Xue-Jun Ge
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China. .,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China.
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Wong ELY, Hiscock SJ, Filatov DA. The Role of Interspecific Hybridisation in Adaptation and Speciation: Insights From Studies in Senecio. FRONTIERS IN PLANT SCIENCE 2022; 13:907363. [PMID: 35812981 PMCID: PMC9260247 DOI: 10.3389/fpls.2022.907363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 06/03/2022] [Indexed: 05/08/2023]
Abstract
Hybridisation is well documented in many species, especially plants. Although hybrid populations might be short-lived and do not evolve into new lineages, hybridisaiton could lead to evolutionary novelty, promoting adaptation and speciation. The genus Senecio (Asteraceae) has been actively used to unravel the role of hybridisation in adaptation and speciation. In this article, we first briefly describe the process of hybridisation and the state of hybridisation research over the years. We then discuss various roles of hybridisation in plant adaptation and speciation illustrated with examples from different Senecio species, but also mention other groups of organisms whenever necessary. In particular, we focus on the genomic and transcriptomic consequences of hybridisation, as well as the ecological and physiological aspects from the hybrids' point of view. Overall, this article aims to showcase the roles of hybridisation in speciation and adaptation, and the research potential of Senecio, which is part of the ecologically and economically important family, Asteraceae.
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Affiliation(s)
- Edgar L. Y. Wong
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
- *Correspondence: Edgar L. Y. Wong,
| | - Simon J. Hiscock
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
- Oxford Botanic Garden and Arboretum, Oxford, United Kingdom
| | - Dmitry A. Filatov
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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Scobeyeva VA, Artyushin IV, Krinitsina AA, Nikitin PA, Antipin MI, Kuptsov SV, Belenikin MS, Omelchenko DO, Logacheva MD, Konorov EA, Samoilov AE, Speranskaya AS. Gene Loss, Pseudogenization in Plastomes of Genus Allium ( Amaryllidaceae), and Putative Selection for Adaptation to Environmental Conditions. Front Genet 2021; 12:674783. [PMID: 34306019 PMCID: PMC8296844 DOI: 10.3389/fgene.2021.674783] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 06/15/2021] [Indexed: 01/07/2023] Open
Abstract
Amaryllidaceae is a large family with more than 1,600 species, belonging to 75 genera. The largest genus—Allium—is vast, comprising about a thousand species. Allium species (as well as other members of the Amaryllidaceae) are widespread and diversified, they are adapted to a wide range of habitats from shady forests to open habitats like meadows, steppes, and deserts. The genes present in chloroplast genomes (plastomes) play fundamental roles for the photosynthetic plants. Plastome traits could thus be associated with geophysical abiotic characteristics of habitats. Most chloroplast genes are highly conserved and are used as phylogenetic markers for many families of vascular plants. Nevertheless, some studies revealed signatures of positive selection in chloroplast genes of many plant families including Amaryllidaceae. We have sequenced plastomes of the following nine Allium (tribe Allieae of Allioideae) species: A. zebdanense, A. moly, A. victorialis, A. macleanii, A. nutans, A. obliquum, A. schoenoprasum, A. pskemense, A. platyspathum, A. fistulosum, A. semenovii, and Nothoscordum bivalve (tribe Leucocoryneae of Allioideae). We compared our data with previously published plastomes and provided our interpretation of Allium plastome genes’ annotations because we found some noteworthy inconsistencies with annotations previously reported. For Allium species we estimated the integral evolutionary rate, counted SNPs and indels per nucleotide position as well as compared pseudogenization events in species of three main phylogenetic lines of genus Allium to estimate whether they are potentially important for plant physiology or just follow the phylogenetic pattern. During examination of the 38 species of Allium and the 11 of other Amaryllidaceae species we found that rps16, rps2, infA, ccsA genes have lost their functionality multiple times in different species (regularly evolutionary events), while the pseudogenization of other genes was stochastic events. We found that the “normal” or “pseudo” state of rps16, rps2, infA, ccsA genes correlates well with the evolutionary line of genus the species belongs to. The positive selection in various NADH dehydrogenase (ndh) genes as well as in matK, accD, and some others were found. Taking into account known mechanisms of coping with excessive light by cyclic electron transport, we can hypothesize that adaptive evolution in genes, coding subunits of NADH-plastoquinone oxidoreductase could be driven by abiotic factors of alpine habitats, especially by intensive light and UV radiation.
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Affiliation(s)
- Victoria A Scobeyeva
- Department of Evolution, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.,Department of Molecular and Biological Physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Ilya V Artyushin
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Anastasiya A Krinitsina
- Department of Higher Plants, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Pavel A Nikitin
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Maxim I Antipin
- Botanical Garden, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Sergei V Kuptsov
- Botanical Garden, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Maxim S Belenikin
- Department of Molecular and Biological Physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Denis O Omelchenko
- Laboratory of Plant Genomics, Institute for Information Transmission Problems, Moscow, Russia
| | - Maria D Logacheva
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Evgenii A Konorov
- Laboratory of Animal Genetics, Vavilov Institute of General Genetics, Russian Academy of Science (RAS), Moscow, Russia
| | - Andrey E Samoilov
- Group of Genomics and Postgenomic Technologies, Central Research Institute of Epidemiology, Moscow, Russia
| | - Anna S Speranskaya
- Department of Higher Plants, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.,Group of Genomics and Postgenomic Technologies, Central Research Institute of Epidemiology, Moscow, Russia
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Loeuille B, Thode V, Siniscalchi C, Andrade S, Rossi M, Pirani JR. Extremely low nucleotide diversity among thirty-six new chloroplast genome sequences from Aldama (Heliantheae, Asteraceae) and comparative chloroplast genomics analyses with closely related genera. PeerJ 2021; 9:e10886. [PMID: 33665028 PMCID: PMC7912680 DOI: 10.7717/peerj.10886] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 01/12/2021] [Indexed: 01/23/2023] Open
Abstract
Aldama (Heliantheae, Asteraceae) is a diverse genus in the sunflower family. To date, nearly 200 Asteraceae chloroplast genomes have been sequenced, but the plastomes of Aldama remain undescribed. Plastomes in Asteraceae usually show little sequence divergence, consequently, our hypothesis is that species of Aldama will be overall conserved. In this study, we newly sequenced 36 plastomes of Aldama and of five species belonging to other Heliantheae genera selected as outgroups (i.e., Dimerostemma asperatum, Helianthus tuberosus, Iostephane heterophylla, Pappobolus lanatus var. lanatus, and Tithonia diversifolia). We analyzed the structure and gene content of the assembled plastomes and performed comparative analyses within Aldama and with other closely related genera. As expected, Aldama plastomes are very conserved, with the overall gene content and orientation being similar in all studied species. The length of the plastome is also consistent and the junction between regions usually contain the same genes and have similar lengths. A large ∼20 kb and a small ∼3 kb inversion were detected in the Large Single Copy (LSC) regions of all assembled plastomes, similarly to other Asteraceae species. The nucleotide diversity is very low, with only 1,509 variable sites in 127,466 bp (i.e., 1.18% of the sites in the alignment of 36 Aldama plastomes, with one of the IRs removed, is variable). Only one gene, rbcL, shows signatures of positive selection. The plastomes of the selected outgroups feature a similar gene content and structure compared to Aldama and also present the two inversions in the LSC region. Deletions of different lengths were observed in the gene ycf2. Multiple SSRs were identified for the sequenced Aldama and outgroups. The phylogenetic analysis shows that Aldama is not monophyletic due to the position of the Mexican species A. dentata. All Brazilian species form a strongly supported clade. Our results bring new understandings into the evolution and diversity of plastomes at the species level.
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Affiliation(s)
- Benoit Loeuille
- Departamento de Botânica, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Verônica Thode
- Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Carolina Siniscalchi
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, United States of America
| | - Sonia Andrade
- Departamento de Genética e Biologia Evolutiva, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Magdalena Rossi
- Departamento de Botânica, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - José Rubens Pirani
- Departamento de Botânica, Universidade de São Paulo, São Paulo, São Paulo, Brazil
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Bernabeu M, Rosselló JA. Molecular Evolution of rbcL in Orthotrichales (Bryophyta): Site Variation, Adaptive Evolution, and Coevolutionary Patterns of Amino Acid Replacements. J Mol Evol 2021; 89:225-237. [PMID: 33611663 DOI: 10.1007/s00239-021-09998-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 01/31/2021] [Indexed: 11/24/2022]
Abstract
Molecular evolution of the large subunit of the RuBisCO enzyme is understudied in early diverging land plants. These groups show morphological and eco-physiological adaptations to the uneven and intermittent distribution of water in the terrestrial environment. This might have prompted a continuous fine-tuning of RuBisCO under a selective pressure modifying the species-specific optima for photosynthesis in contrasting microdistributions and environmental niches. To gain a better insight into the molecular evolution of RuBisCO large subunits, the aim of this study was to assess the pattern of evolutionary change in the amino acid residues in a monophyletic group of Bryophyta (Orthotrichaceae). Tests for positive, neutral, or purifying selection at the amino acid level were assessed by comparing rates (ω) of non-synonymous (dN) and synonymous (dS) nucleotide substitutions along a Maximum Likelihood phylogenetic tree. Molecular adaptation tests using likelihood ratio tests, reconstruction of ancestral amino acid sites, and intra-protein coevolution analyses were performed. Variable amino acid sites (39) were unevenly distributed across the LSU. The residues are located on rbcL sites that are highly variable in higher plants and close to key regions implying dimer-dimer (L2L2), RuBisCO-activase interactions, and conformational functions during catalysis. Ten rbcL sites (32, 33, 91, 230, 247, 251, 255, 424, 449 and 475) have been identified by the Bayesian Empirical Bayes inference to be under positive selection and under adaptive evolution under the M8 model. The pattern of amino acid variation suggests that it is not lineage specific, but rather representative of a case of convergent evolution, suggesting recurrent changes that potentially favor the same amino acid substitutions that are likely optimized the RuBisCO activity.
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Affiliation(s)
- Moisès Bernabeu
- Departament de Genètica, Universitat de València, c/ Doctor Moliner 50, Burjassot, 46100, ,València, Spain
| | - Josep A Rosselló
- Jardín Botánico, ICBiBE, Universitat de València, c/ Quart 80, 46008, València, Spain.
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Androsiuk P, Jastrzębski JP, Paukszto Ł, Makowczenko K, Okorski A, Pszczółkowska A, Chwedorzewska KJ, Górecki R, Giełwanowska I. Evolutionary dynamics of the chloroplast genome sequences of six Colobanthus species. Sci Rep 2020; 10:11522. [PMID: 32661280 PMCID: PMC7359349 DOI: 10.1038/s41598-020-68563-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 06/25/2020] [Indexed: 11/08/2022] Open
Abstract
The complete plastome sequences of six species were sequenced to better understand the evolutionary relationships and mutation patterns in the chloroplast genome of the genus Colobanthus. The length of the chloroplast genome sequences of C. acicularis, C. affinis, C. lycopodioides, C. nivicola, C. pulvinatus and C. subulatus ranged from 151,050 to 151,462 bp. The quadripartite circular structure of these genome sequences has the same overall organization and gene content with 73 protein-coding genes, 30 tRNA genes, four rRNA genes and five conserved chloroplast open reading frames. A total of 153 repeat sequences were revealed. Forward repeats were dominant, whereas complementary repeats were found only in C. pulvinatus. The mononucleotide SSRs composed of A/T units were most common, and hexanucleotide SSRs were detected least often. Eleven highly variable regions which could be utilized as potential markers for phylogeny reconstruction, species identification or phylogeography were identified within Colobanthus chloroplast genomes. Seventy-three protein-coding genes were used in phylogenetic analyses. Reconstructed phylogeny was consistent with the systematic position of the studied species, and the representatives of the same genus were grouped in one clade. All studied Colobanthus species formed a single group and C. lycopodioides was least similar to the remaining species.
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Affiliation(s)
- Piotr Androsiuk
- Department of Plant Physiology, Genetics and Biotechnology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 1A, 10-719, Olsztyn, Poland.
| | - Jan Paweł Jastrzębski
- Department of Plant Physiology, Genetics and Biotechnology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 1A, 10-719, Olsztyn, Poland
| | - Łukasz Paukszto
- Department of Plant Physiology, Genetics and Biotechnology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 1A, 10-719, Olsztyn, Poland
| | - Karol Makowczenko
- Department of Plant Physiology, Genetics and Biotechnology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 1A, 10-719, Olsztyn, Poland
| | - Adam Okorski
- Department of Entomology, Phytopathology and Molecular Diagnostics, Faculty of Environmental Management and Agriculture, University of Warmia and Mazury in Olsztyn, ul. Prawocheńskiego 17, 10-720, Olsztyn, Poland
| | - Agnieszka Pszczółkowska
- Department of Entomology, Phytopathology and Molecular Diagnostics, Faculty of Environmental Management and Agriculture, University of Warmia and Mazury in Olsztyn, ul. Prawocheńskiego 17, 10-720, Olsztyn, Poland
| | | | - Ryszard Górecki
- Department of Plant Physiology, Genetics and Biotechnology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 1A, 10-719, Olsztyn, Poland
| | - Irena Giełwanowska
- Department of Plant Physiology, Genetics and Biotechnology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 1A, 10-719, Olsztyn, Poland
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Somaratne Y, Guan DL, Abbood NN, Zhao L, Wang WQ, Xu SQ. Comparison of the Complete Eragrostis pilosa Chloroplast Genome with Its Relatives in Eragrostideae (Chloridoideae; Poaceae). PLANTS (BASEL, SWITZERLAND) 2019; 8:E485. [PMID: 31717580 PMCID: PMC6918254 DOI: 10.3390/plants8110485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 10/30/2019] [Accepted: 11/06/2019] [Indexed: 01/18/2023]
Abstract
Eragrostis of the tribe Eragrostideae is a taxonomically complex genus, because of its polyploid nature and the presence of similar morphological characters among its species. However, the relationship between these morphologically indistinguishable species at the genomic level has not yet been investigated. Here, we report the complete chloroplast genome of E. pilosa and compare its genome structures, gene contents, simple sequence repeats (SSRs), sequence divergence, codon usage bias, and Kimura 2-parameter (K2P) interspecific genetic distances with those of other Eragrostideae species. The E. pilosa chloroplast genome was 134,815 bp in length and contained 132 genes and four regions, including a large single-copy region (80,100 bp), a small single-copy region (12,661 bp), and a pair of inverted repeats (21,027 bp). The average nucleotide diversity between E. pilosa and E. tef was estimated to be 0.011, and 0.01689 among all species. The minimum and maximum K2P interspecific genetic distance values were identified in psaA (0.007) and matK (0.029), respectively. Of 45 SSRs, eight were shared with E. tef, all of which were in the LSC region. Phylogenetic analysis resolved the monophyly of the sampled Eragrostis species and confirmed the close relationship between E. pilosa and E. tef. This study provides useful chlorophyll genomic information for further species identification and phylogenetic reconstruction of Eragrostis species.
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Affiliation(s)
- Yamuna Somaratne
- College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China
| | - De-Long Guan
- College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China
| | - Nibras Najm Abbood
- College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China
| | - Liang Zhao
- College of Life Sciences, Northwest A & F University, Yangling 712100, China
| | - Wen-Qiang Wang
- College of Life Sciences, Yan'an University, Yan'an 716000, China
| | - Sheng-Quan Xu
- College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China
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Yao X, Tan YH, Yang JB, Wang Y, Corlett RT, Manen JF. Exceptionally high rates of positive selection on the rbcL gene in the genus Ilex (Aquifoliaceae). BMC Evol Biol 2019; 19:192. [PMID: 31638910 PMCID: PMC6805373 DOI: 10.1186/s12862-019-1521-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 09/27/2019] [Indexed: 12/26/2022] Open
Abstract
Background The genus Ilex (Aquifoliaceae) has a near-cosmopolitan distribution in mesic habitats from tropical to temperate lowlands and in alpine forests. It has a high rate of hybridization and plastid capture, and comprises four geographically structured plastid groups. A previous study showed that the plastid rbcL gene, coding for the large subunit of Rubisco, has a particularly high rate of non-synonymous substitutions in Ilex, when compared with other plant lineages. This suggests a strong positive selection on rbcL, involved in yet unknown adaptations. We therefore investigated positive selection on rbcL in 240 Ilex sequences from across the global range. Results The rbcL gene shows a much higher rate of positive selection in Ilex than in any other plant lineage studied so far (> 3000 species) by tests in both PAML and SLR. Most positively selected residues are on the surface of the folded large subunit, suggesting interaction with other subunits and associated chaperones, and coevolution between positively selected residues is prevalent, indicating compensatory mutations to recover molecular stability. Coevolution between positively selected sites to restore global stability is common. Conclusions This study has confirmed the predicted high incidence of positively selected residues in rbcL in Ilex, and shown that this is higher than in any other plant lineage studied so far. The causes and consequences of this high incidence are unclear, but it is probably associated with the similarly high incidence of hybridization and introgression in Ilex, even between distantly related lineages, resulting in large cytonuclear discordance in the phylogenies.
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Affiliation(s)
- Xin Yao
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, 666303, Yunnan, China. .,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China.
| | - Yun-Hong Tan
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, 666303, Yunnan, China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China.,Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Yezin, Nay Pyi Taw, Myanmar
| | - Jun-Bo Yang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Yan Wang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, 666303, Yunnan, China
| | - Richard T Corlett
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, 666303, Yunnan, China. .,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China.
| | - Jean-François Manen
- Laboratoire de Systématique Végétale et Biodiversité, University of Geneva (retired), Chemin de l'Impératrice 1, CH-1292, Chambésy, Switzerland.
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Hermida-Carrera C, Fares MA, Fernández Á, Gil-Pelegrín E, Kapralov MV, Mir A, Molins A, Peguero-Pina JJ, Rocha J, Sancho-Knapik D, Galmés J. Positively selected amino acid replacements within the RuBisCO enzyme of oak trees are associated with ecological adaptations. PLoS One 2017; 12:e0183970. [PMID: 28859145 PMCID: PMC5578625 DOI: 10.1371/journal.pone.0183970] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 08/15/2017] [Indexed: 12/29/2022] Open
Abstract
Phylogenetic analysis by maximum likelihood (PAML) has become the standard approach to study positive selection at the molecular level, but other methods may provide complementary ways to identify amino acid replacements associated with particular conditions. Here, we compare results of the decision tree (DT) model method with ones of PAML using the key photosynthetic enzyme RuBisCO as a model system to study molecular adaptation to particular ecological conditions in oaks (Quercus). We sequenced the chloroplast rbcL gene encoding RuBisCO large subunit in 158 Quercus species, covering about a third of the global genus diversity. It has been hypothesized that RuBisCO has evolved differentially depending on the environmental conditions and leaf traits governing internal gas diffusion patterns. Here, we show, using PAML, that amino acid replacements at the residue positions 95, 145, 251, 262 and 328 of the RuBisCO large subunit have been the subject of positive selection along particular Quercus lineages associated with the leaf traits and climate characteristics. In parallel, the DT model identified amino acid replacements at sites 95, 219, 262 and 328 being associated with the leaf traits and climate characteristics, exhibiting partial overlap with the results obtained using PAML.
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Affiliation(s)
- Carmen Hermida-Carrera
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | - Mario A. Fares
- Integrative and Systems Biology Group, Department of Abiotic Stress, Instituto de Biología Molecular y Celular de Plantas (CSIC–UPV), Valencia, Spain
- Department of Genetics, University of Dublin, Trinity College Dublin, Dublin 2, Ireland
| | - Ángel Fernández
- Unidad de Recursos Forestales, C.I.T.A. de Aragón, Zaragoza, Spain
| | | | - Maxim V. Kapralov
- School of Natural and Environmental Sciences, Newcastle University, Newcastle-Upon-Tyne, United Kingdom
| | - Arnau Mir
- Computational Biology and Bioinformatics Research Group, Department of Mathematics and Computer Science, Universitat de les Illes Balears, Palma, Balearic Islands, Spain
| | - Arántzazu Molins
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | | | - Jairo Rocha
- Computational Biology and Bioinformatics Research Group, Department of Mathematics and Computer Science, Universitat de les Illes Balears, Palma, Balearic Islands, Spain
| | | | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
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Scoffoni C, Kunkle J, Pasquet-Kok J, Vuong C, Patel AJ, Montgomery RA, Givnish TJ, Sack L. Light-induced plasticity in leaf hydraulics, venation, anatomy, and gas exchange in ecologically diverse Hawaiian lobeliads. THE NEW PHYTOLOGIST 2015; 207:43-58. [PMID: 25858142 DOI: 10.1111/nph.13346] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 01/21/2015] [Indexed: 06/04/2023]
Abstract
Leaf hydraulic conductance (Kleaf ) quantifies the capacity of a leaf to transport liquid water and is a major constraint on light-saturated stomatal conductance (gs ) and photosynthetic rate (Amax ). Few studies have tested the plasticity of Kleaf and anatomy across growth light environments. These provided conflicting results. The Hawaiian lobeliads are an excellent system to examine plasticity, given the striking diversity in the light regimes they occupy, and their correspondingly wide range of Amax , allowing maximal carbon gain for success in given environments. We measured Kleaf , Amax , gs and leaf anatomical and structural traits, focusing on six species of lobeliads grown in a common garden under two irradiances (300/800 μmol photons m(-2) s(-1) ). We tested hypotheses for light-induced plasticity in each trait based on expectations from optimality. Kleaf , Amax , and gs differed strongly among species. Sun/shade plasticity was observed in Kleaf , Amax, and numerous traits relating to lamina and xylem anatomy, venation, and composition, but gs was not plastic with growth irradiance. Species native to higher irradiance showed greater hydraulic plasticity. Our results demonstrate that a wide set of leaf hydraulic, stomatal, photosynthetic, anatomical, and structural traits tend to shift together during plasticity and adaptation to diverse light regimes, optimizing performance from low to high irradiance.
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Affiliation(s)
- Christine Scoffoni
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Justin Kunkle
- Office of Research, Western Kentucky University, 1906 College Heights Blvd #11026, Bowling Green, KY, 42101, USA
| | - Jessica Pasquet-Kok
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Christine Vuong
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Amish J Patel
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Rebecca A Montgomery
- Department of Forest Resources, University of Minnesota, 1530 Cleveland Avenue North, Saint Paul, MN, 55108, USA
| | - Thomas J Givnish
- Department of Botany, University of Wisconsin Madison, Madison, WI, 53706, USA
| | - Lawren Sack
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
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Bock DG, Andrew RL, Rieseberg LH. On the adaptive value of cytoplasmic genomes in plants. Mol Ecol 2014; 23:4899-911. [PMID: 25223488 DOI: 10.1111/mec.12920] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 09/08/2014] [Accepted: 09/10/2014] [Indexed: 01/30/2023]
Abstract
Is DNA variation maintained in organelle genomes selectively neutral? The answer to this question has important implications for many aspects of ecology and evolution. While traditionally the answer has been 'yes', recent studies in animals have shown that, on the contrary, mitochondrial DNA polymorphism is frequently adaptive. In plants, however, the neutrality assumption has not been strongly challenged. Here, we begin with a critical evaluation of arguments in favour of this long-held view. We then discuss the latest empirical evidence for the opposing prediction that sequence variation in plant cytoplasmic genomes is frequently adaptive. While outstanding research progress is being made towards understanding this fundamental topic, we highlight the need for studies that combine information ranging from field experiments to physiology to molecular evolutionary biology. Such an interdisciplinary approach provides a means for determining the frequency, drivers and evolutionary significance of adaptive organelle DNA variation.
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Affiliation(s)
- Dan G Bock
- Department of Botany, Biodiversity Research Centre, University of British Columbia, 3529-6270 University Blvd., Vancouver, British Columbia, Canada, V6T 1Z4
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15
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Galmés J, Andralojc PJ, Kapralov MV, Flexas J, Keys AJ, Molins A, Parry MAJ, Conesa MÀ. Environmentally driven evolution of Rubisco and improved photosynthesis and growth within the C3 genus Limonium (Plumbaginaceae). THE NEW PHYTOLOGIST 2014; 203:989-99. [PMID: 24861241 DOI: 10.1111/nph.12858] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 04/23/2014] [Indexed: 05/22/2023]
Abstract
Carbon assimilation by most ecosystems requires ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Its kinetic parameters are likely to have evolved in parallel with intracellular CO2 availability, with the result that faster forms of Rubisco occur in species with CO2 -concentrating mechanisms. The Rubisco catalytic properties were determined and evaluated in relation to growth and carbon assimilation capacity in Mediterranean Limonium species, inhabiting severe stress environments. Significant kinetic differences between closely related species depended on two amino acid substitutions at functionally important residues 309 and 328 within the Rubisco large subunit. The Rubisco of species facing the largest CO2 restrictions during drought had relatively high affinity for CO2 (low Michaelis-Menten constant for CO2 Kc) but low maximum rates of carboxylation (kcatc), while the opposite was found for species that maintained higher CO2 concentrations under similar conditions. Rubisco kinetic characteristics were correlated with photosynthetic rate in both well-watered and drought-stressed plants. Moreover, the drought-mediated decrease in plant biomass accumulation was consistently lower in species with higher Rubisco carboxylase catalytic efficiency (kcatc/Kc). The present study is the first demonstration of Rubisco adaptation during species diversification within closely related C3 plants, revealing a direct relationship between Rubisco molecular evolution and the biomass accumulation of closely related species subjected to unfavourable conditions.
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Affiliation(s)
- Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Balearic Islands, Spain
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Zhao Y, Yin J, Guo H, Zhang Y, Xiao W, Sun C, Wu J, Qu X, Yu J, Wang X, Xiao J. The complete chloroplast genome provides insight into the evolution and polymorphism of Panax ginseng. FRONTIERS IN PLANT SCIENCE 2014; 5:696. [PMID: 25642231 PMCID: PMC4294130 DOI: 10.3389/fpls.2014.00696] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 11/23/2014] [Indexed: 05/21/2023]
Abstract
Panax ginseng C.A. Meyer (P. ginseng) is an important medicinal plant and is often used in traditional Chinese medicine. With next generation sequencing (NGS) technology, we determined the complete chloroplast genome sequences for four Chinese P. ginseng strains, which are Damaya (DMY), Ermaya (EMY), Gaolishen (GLS), and Yeshanshen (YSS). The total chloroplast genome sequence length for DMY, EMY, and GLS was 156,354 bp, while that for YSS was 156,355 bp. Comparative genomic analysis of the chloroplast genome sequences indicate that gene content, GC content, and gene order in DMY are quite similar to its relative species, and nucleotide sequence diversity of inverted repeat region (IR) is lower than that of its counterparts, large single copy region (LSC) and small single copy region (SSC). A comparison among these four P. ginseng strains revealed that the chloroplast genome sequences of DMY, EMY, and GLS were identical and YSS had a 1-bp insertion at base 5472. To further study the heterogeneity in chloroplast genome during domestication, high-resolution reads were mapped to the genome sequences to investigate the differences at the minor allele level; 208 minor allele sites with minor allele frequencies (MAF) of ≥0.05 were identified. The polymorphism site numbers per kb of chloroplast genome sequence for DMY, EMY, GLS, and YSS were 0.74, 0.59, 0.97, and 1.23, respectively. All the minor allele sites located in LSC and IR regions, and the four strains showed the same variation types (substitution base or indel) at all identified polymorphism sites. Comparison results of heterogeneity in the chloroplast genome sequences showed that the minor allele sites on the chloroplast genome were undergoing purifying selection to adapt to changing environment during domestication process. A study of P. ginseng chloroplast genome with particular focus on minor allele sites would aid in investigating the dynamics on the chloroplast genomes and different P. ginseng strains typing.
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Affiliation(s)
- Yongbing Zhao
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
- University of Chinese Academy of SciencesBeijing, China
| | - Jinlong Yin
- School of Pharmaceutical Sciences, Changchun University of Chinese MedicineChangchun, China
| | - Haiyan Guo
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
| | - Yuyu Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
- University of Chinese Academy of SciencesBeijing, China
| | - Wen Xiao
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
- University of Chinese Academy of SciencesBeijing, China
| | - Chen Sun
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
- University of Chinese Academy of SciencesBeijing, China
| | - Jiayan Wu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
| | - Xiaobo Qu
- School of Pharmaceutical Sciences, Changchun University of Chinese MedicineChangchun, China
| | - Jun Yu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
| | - Xumin Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
- *Correspondence: Jingfa Xiao and Xumin Wang, Beijing Institute of Genomics, Chinese Academy of Sciences. NO.1 Beichen West Road, Chaoyang District, Beijing 100101, China e-mail: ;
| | - Jingfa Xiao
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of SciencesBeijing, China
- *Correspondence: Jingfa Xiao and Xumin Wang, Beijing Institute of Genomics, Chinese Academy of Sciences. NO.1 Beichen West Road, Chaoyang District, Beijing 100101, China e-mail: ;
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Abstract
"Explosive" adaptive radiations on islands remain one of the most puzzling evolutionary phenomena and the evolutionary genetic processes behind such radiations remain unclear. Rapid morphological and ecological evolution during island radiations suggests that many genes may be under fairly strong selection, although this remains untested. Here, we report that during a rapid recent diversification in the Hawaiian endemic plant genus Schiedea (Caryophyllaceae), 5 in 36 studied genes evolved under positive selection. Positively selected genes are involved in defence mechanisms, photosynthesis, and reproduction. Comparison with eight mainland plant groups demonstrates both the relaxation of purifying selection and more widespread positive selection in Hawaiian Schiedea. This provides compelling evidence that adaptive evolution of protein-coding genes may play a significant role during island adaptive radiations.
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Affiliation(s)
| | | | - Dmitry A. Filatov
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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18
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Greiner S, Bock R. Tuning a ménage à trois: Co-evolution and co-adaptation of nuclear and organellar genomes in plants. Bioessays 2013; 35:354-65. [DOI: 10.1002/bies.201200137] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kapralov MV, Smith JAC, Filatov DA. Rubisco evolution in C₄ eudicots: an analysis of Amaranthaceae sensu lato. PLoS One 2012; 7:e52974. [PMID: 23285238 PMCID: PMC3527620 DOI: 10.1371/journal.pone.0052974] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 11/26/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyses the key reaction in the photosynthetic assimilation of CO₂. In C₄ plants CO₂ is supplied to Rubisco by an auxiliary CO₂-concentrating pathway that helps to maximize the carboxylase activity of the enzyme while suppressing its oxygenase activity. As a consequence, C₄ Rubisco exhibits a higher maximum velocity but lower substrate specificity compared with the C₃ enzyme. Specific amino-acids in Rubisco are associated with C₄ photosynthesis in monocots, but it is not known whether selection has acted on Rubisco in a similar way in eudicots. METHODOLOGY/PRINCIPAL FINDINGS We investigated Rubisco evolution in Amaranthaceae sensu lato (including Chenopodiaceae), the third-largest family of C₄ plants, using phylogeny-based maximum likelihood and Bayesian methods to detect Darwinian selection on the chloroplast rbcL gene in a sample of 179 species. Two Rubisco residues, 281 and 309, were found to be under positive selection in C₄ Amaranthaceae with multiple parallel replacements of alanine by serine at position 281 and methionine by isoleucine at position 309. Remarkably, both amino-acids have been detected in other C₄ plant groups, such as C₄ monocots, illustrating a striking parallelism in molecular evolution. CONCLUSIONS/SIGNIFICANCE Our findings illustrate how simple genetic changes can contribute to the evolution of photosynthesis and strengthen the hypothesis that parallel amino-acid replacements are associated with adaptive changes in Rubisco.
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Affiliation(s)
- Maxim V Kapralov
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, United Kingdom.
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20
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Decoupling of differentiation between traits and their underlying genes in response to divergent selection. Heredity (Edinb) 2011; 108:375-85. [PMID: 21915150 DOI: 10.1038/hdy.2011.81] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We dissected the relationship between genetic differentiation (Q(ST)) for a trait and its underlying genes (G(STq), differentiation for a quantitative locus) in an evolutionary context, with the aim of identifying the conditions in which these two measurements are decoupled. We used two parameters (θ(B) and θ(W)) scaling the contributions of inter- and intrapopulation allelic covariation between genes controlling the trait of interest. We monitored the changes in θ(B) and θ(W), Q(ST) and G(STq) over successive generations of divergent and stabilizing selection, in simulations for an outcrossing species with extensive gene flow. The dynamics of these parameters are characterized by two phases. Initially, during the earliest generations, differentiation of the trait increases very rapidly and the principal and immediate driver of Q(ST) is θ(B). During subsequent generations, G(STq) increases steadily and makes an equal contribution to Q(ST). These results show that selection first captures beneficial allelic associations at different loci at different populations, and then targets changes in allelic frequencies. The same patterns are observed when environmental change modifies divergent selection, as shown by the very rapid response of θ(B) to the changes of selection regimes. We compare our results with previous experimental findings and consider their relevance to the detection of molecular signatures of natural selection.
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Marais GAB, Forrest A, Kamau E, Käfer J, Daubin V, Charlesworth D. Multiple nuclear gene phylogenetic analysis of the evolution of dioecy and sex chromosomes in the genus Silene. PLoS One 2011; 6:e21915. [PMID: 21853022 PMCID: PMC3154253 DOI: 10.1371/journal.pone.0021915] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 06/08/2011] [Indexed: 11/18/2022] Open
Abstract
In the plant genus Silene, separate sexes and sex chromosomes are believed to have evolved twice. Silene species that are wholly or largely hermaphroditic are assumed to represent the ancestral state from which dioecy evolved. This assumption is important for choice of outgroup species for inferring the genetic and chromosomal changes involved in the evolution of dioecy, but is mainly based on data from a single locus (ITS). To establish the order of events more clearly, and inform outgroup choice, we therefore carried out (i) multi-nuclear-gene phylogenetic analyses of 14 Silene species (including 7 hermaphrodite or gynodioecious species), representing species from both Silene clades with dioecious members, plus a more distantly related outgroup, and (ii) a BayesTraits character analysis of the evolution of dioecy. We confirm two origins of dioecy within this genus in agreement with recent work on comparing sex chromosomes from both clades with dioecious species. We conclude that sex chromosomes evolved after the origin of Silene and within a clade that includes only S. latifolia and its closest relatives. We estimate that sex chromosomes emerged soon after the split with the ancestor of S. viscosa, the probable closest non-dioecious S. latifolia relative among the species included in our study.
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Affiliation(s)
- Gabriel A B Marais
- Laboratoire de Biométrie et Biologie évolutive, UMR5558, Université Lyon 1, Centre National de la Recherche Scientifique, Villeurbanne, France.
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Fan S, Elmer KR, Meyer A. Positive Darwinian selection drives the evolution of the morphology-related gene, EPCAM, in particularly species-rich lineages of African cichlid fishes. J Mol Evol 2011; 73:1-9. [PMID: 21811860 DOI: 10.1007/s00239-011-9452-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 07/07/2011] [Indexed: 12/23/2022]
Abstract
The study of genetic evolution within the context of adaptive radiations offers insights to genes and selection pressures that result in rapid morphological change. Cichlid fishes are very species-rich and variable in coloration, behavior, and morphology, and so provide a classical model system for studying the genetics of adaptive radiation. In this study, we researched the evolution of the epithelial cell adhesion molecule (EPCAM), a candidate gene for the adaptive evolution of morphology broadly, and skin development specifically, in fishes. We compared EPCAM gene sequences from a rapidly speciating African cichlid lineage (the haplochromines), a species-poor African lineage (Nile tilapia Oreochromis niloticus), and a very young adaptive radiation in the Neotropics (sympatric crater lake Midas cichlids, Amphilophus sp.). Our results, based on a hierarchy of evolutionary analyses of nucleotide substitution, demonstrate that there are different selection pressures on the EPCAM gene among the cichlid lineages. Several waves of positive natural selection were identified not only on the terminal branches, but also on ancestral branches. Interestingly, significant positive or directional selection was found in the haplochromine cichlids only but not the comparatively species-poor tilapia lineage. We hypothesize that the strong signal of selection in the ancestral African cichlid lineage coincided with the transition from riverine to lacustrine habitat. The two neotropical species for which we collected new sequence data were invariant in the EPCAM locus. Our results suggest that functional changes promoted by positive Darwinian selection are widespread in the EPCAM gene during African cichlid evolution.
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Affiliation(s)
- Shaohua Fan
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätstrasse 10, 78457 Constance, Germany
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Sen L, Fares MA, Liang B, Gao L, Wang B, Wang T, Su YJ. Molecular evolution of rbcL in three gymnosperm families: identifying adaptive and coevolutionary patterns. Biol Direct 2011; 6:29. [PMID: 21639885 PMCID: PMC3129321 DOI: 10.1186/1745-6150-6-29] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 06/03/2011] [Indexed: 11/10/2022] Open
Abstract
Background The chloroplast-localized ribulose-1, 5-biphosphate carboxylase/oxygenase (Rubisco), the primary enzyme responsible for autotrophy, is instrumental in the continual adaptation of plants to variations in the concentrations of CO2. The large subunit (LSU) of Rubisco is encoded by the chloroplast rbcL gene. Although adaptive processes have been previously identified at this gene, characterizing the relationships between the mutational dynamics at the protein level may yield clues on the biological meaning of such adaptive processes. The role of such coevolutionary dynamics in the continual fine-tuning of RbcL remains obscure. Results We used the timescale and phylogenetic analyses to investigate and search for processes of adaptive evolution in rbcL gene in three gymnosperm families, namely Podocarpaceae, Taxaceae and Cephalotaxaceae. To understand the relationships between regions identified as having evolved under adaptive evolution, we performed coevolutionary analyses using the software CAPS. Importantly, adaptive processes were identified at amino acid sites located on the contact regions among the Rubisco subunits and on the interface between Rubisco and its activase. Adaptive amino acid replacements at these regions may have optimized the holoenzyme activity. This hypothesis was pinpointed by evidence originated from our analysis of coevolution that supported the correlated evolution between Rubisco and its activase. Interestingly, the correlated adaptive processes between both these proteins have paralleled the geological variation history of the concentration of atmospheric CO2. Conclusions The gene rbcL has experienced bursts of adaptations in response to the changing concentration of CO2 in the atmosphere. These adaptations have emerged as a result of a continuous dynamic of mutations, many of which may have involved innovation of functional Rubisco features. Analysis of the protein structure and the functional implications of such mutations put forward the conclusion that this evolutionary scenario has been possible through a complex interplay between adaptive mutations, often structurally destabilizing, and compensatory mutations. Our results unearth patterns of evolution that have likely optimized the Rubisco activity and uncover mutational dynamics useful in the molecular engineering of enzymatic activities. Reviewers This article was reviewed by Prof. Christian Blouin (nominated by Dr W Ford Doolittle), Dr Endre Barta (nominated by Dr Sandor Pongor), and Dr Nicolas Galtier.
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Affiliation(s)
- Lin Sen
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
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Budar F, Roux F. The role of organelle genomes in plant adaptation: time to get to work! PLANT SIGNALING & BEHAVIOR 2011; 6:635-9. [PMID: 21499027 PMCID: PMC3172827 DOI: 10.4161/psb.6.5.14524] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 01/28/2011] [Indexed: 05/25/2023]
Abstract
That organellar genome variation can play a role in plant adaptation has been suggested by several lines of evidence, including cytoplasm capture, cytoplasm effects in local adaptation, and positive selection in a chloroplast gene. In-depth analysis and better understanding of the genetic basis of plant adaptation is becoming a main objective in plant science. Arabidopsis thaliana has all the required characteristics to be used as a model for obtaining knowledge on the mechanisms underlying the role of organelles in plant adaptation. The availability of the appropriate tools and materials for assessing organelle genetic variation will open up new opportunities for developing novel breeding strategies.
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Affiliation(s)
- Françoise Budar
- INRA, Institut Jean-Pierre Bourgin, Versailles cedex, France.
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GREINER STEPHAN, RAUWOLF UWE, MEURER JÖRG, HERRMANN REINHOLDG. The role of plastids in plant speciation. Mol Ecol 2011; 20:671-91. [DOI: 10.1111/j.1365-294x.2010.04984.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kapralov MV, Kubien DS, Andersson I, Filatov DA. Changes in Rubisco kinetics during the evolution of C4 photosynthesis in Flaveria (Asteraceae) are associated with positive selection on genes encoding the enzyme. Mol Biol Evol 2010; 28:1491-503. [PMID: 21172830 DOI: 10.1093/molbev/msq335] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rubisco, the primary photosynthetic carboxylase, evolved 3-4 billion years ago in an anaerobic, high CO(2) atmosphere. The combined effect of low CO(2) and high O(2) levels in the modern atmosphere, and the inability of Rubisco to distinguish completely between CO(2) and O(2), leads to the occurrence of an oxygenation reaction that reduces the efficiency of photosynthesis. Among land plants, C(4) photosynthesis largely solves this problem by facilitating a high CO(2)/O(2) ratio at the site of Rubisco that resembles the atmosphere in which the ancestral enzyme evolved. The prediction that such conditions favor Rubiscos with higher kcat(CO2) and lower CO(2)/O(2) specificity (S(C/O)) is well supported, but the structural basis for the differences between C(3) and C(4) Rubiscos is not clear. Flaveria (Asteraceae) includes C(3), C(3)-C(4) intermediate, and C(4) species with kinetically distinct Rubiscos, providing a powerful system in which to study the biochemical transition of Rubisco during the evolution from C(3) to C(4) photosynthesis. We analyzed the molecular evolution of chloroplast rbcL and nuclear rbcS genes encoding the large subunit (LSu) and small subunit (SSu) of Rubisco from 15 Flaveria species. We demonstrate positive selection on both subunits, although selection is much stronger on the LSu. In Flaveria, two positively selected LSu amino acid substitutions, M309I and D149A, distinguish C(4) Rubiscos from the ancestral C(3) species and statistically account for much of the kinetic difference between the two groups. However, although Flaveria lacks a characteristic "C(4)" SSu, our data suggest that specific residue substitutions in the SSu are correlated with the kinetic properties of Rubisco in this genus.
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Affiliation(s)
- Maxim V Kapralov
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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DIXON CJ, KAPRALOV MV, FILATOV DA. Gene flow and species cohesion following the spread of Schiedea globosa (Caryophyllaceae) across the Hawaiian Islands. J Evol Biol 2010; 24:1-11. [DOI: 10.1111/j.1420-9101.2010.02128.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Adaptive evolution of rbcL in Conocephalum (Hepaticae, bryophytes). Gene 2009; 441:169-75. [DOI: 10.1016/j.gene.2008.11.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 10/31/2008] [Accepted: 11/01/2008] [Indexed: 11/21/2022]
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Iida S, Miyagi A, Aoki S, Ito M, Kadono Y, Kosuge K. Molecular adaptation of rbcL in the heterophyllous aquatic plant Potamogeton. PLoS One 2009; 4:e4633. [PMID: 19247501 PMCID: PMC2646136 DOI: 10.1371/journal.pone.0004633] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Accepted: 12/31/2008] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Heterophyllous aquatic plants show marked phenotypic plasticity. They adapt to environmental changes by producing different leaf types: submerged, floating and terrestrial leaves. By contrast, homophyllous plants produce only submerged leaves and grow entirely underwater. Heterophylly and submerged homophylly evolved under selective pressure modifying the species-specific optima for photosynthesis, but little is known about the evolutionary outcome of habit. Recent evolutionary analyses suggested that rbcL, a chloroplast gene that encodes a catalytic subunit of RuBisCO, evolves under positive selection in most land plant lineages. To examine the adaptive evolutionary process linked to heterophylly or homophylly, we analyzed positive selection in the rbcL sequences of ecologically diverse aquatic plants, Japanese Potamogeton. PRINCIPAL FINDINGS Phylogenetic and maximum likelihood analyses of codon substitution models indicated that Potamogeton rbcL has evolved under positive Darwinian selection. The positive selection has operated specifically in heterophyllous lineages but not in homophyllous ones in the branch-site models. This suggests that the selective pressure on this chloroplast gene was higher for heterophyllous lineages than for homophyllous lineages. The replacement of 12 amino acids occurred at structurally important sites in the quaternary structure of RbcL, two of which (residue 225 and 281) were identified as potentially under positive selection. CONCLUSIONS/SIGNIFICANCE Our analysis did not show an exact relationship between the amino acid replacements and heterophylly or homophylly but revealed that lineage-specific positive selection acted on the Potamogeton rbcL. The contrasting ecological conditions between heterophyllous and homophyllous plants have imposed different selective pressures on the photosynthetic system. The increased amino acid replacement in RbcL may reflect the continuous fine-tuning of RuBisCO under varying ecological conditions.
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Affiliation(s)
- Satoko Iida
- Research Center for Environmental Genomics, Kobe University, Kobe, Hyogo, Japan.
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Fucile G, Falconer S, Christendat D. Evolutionary diversification of plant shikimate kinase gene duplicates. PLoS Genet 2008; 4:e1000292. [PMID: 19057671 PMCID: PMC2593004 DOI: 10.1371/journal.pgen.1000292] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 11/03/2008] [Indexed: 01/03/2023] Open
Abstract
Shikimate kinase (SK; EC 2.7.1.71) catalyzes the fifth reaction of the shikimate pathway, which directs carbon from the central metabolism pool to a broad range of secondary metabolites involved in plant development, growth, and stress responses. In this study, we demonstrate the role of plant SK gene duplicate evolution in the diversification of metabolic regulation and the acquisition of novel and physiologically essential function. Phylogenetic analysis of plant SK homologs resolves an orthologous cluster of plant SKs and two functionally distinct orthologous clusters. These previously undescribed genes, shikimate kinase-like 1 (SKL1) and -2 (SKL2), do not encode SK activity, are present in all major plant lineages, and apparently evolved under positive selection following SK gene duplication over 400 MYA. This is supported by functional assays using recombinant SK, SKL1, and SKL2 from Arabidopsis thaliana (At) and evolutionary analyses of the diversification of SK-catalytic and -substrate binding sites based on theoretical structure models. AtSKL1 mutants yield albino and novel variegated phenotypes, which indicate SKL1 is required for chloroplast biogenesis. Extant SKL2 sequences show a strong genetic signature of positive selection, which is enriched in a protein–protein interaction module not found in other SK homologs. We also report the first kinetic characterization of plant SKs and show that gene expression diversification among the AtSK inparalogs is correlated with developmental processes and stress responses. This study examines the functional diversification of ancient and recent plant SK gene duplicates and highlights the utility of SKs as scaffolds for functional innovation. Gene duplicates provide an opportunity for functional innovation by buffering their ancestral function. Mutations or genomic rearrangements altering when and where the duplicates are expressed, or the structure/function of the products encoded by the genes, can provide a selective advantage to the organism and are subsequently retained. In this study, we demonstrate that duplicates of genes encoding the metabolic enzyme shikimate kinase (SK) in plants have evolved to acquire novel gene product functions and novel gene expression patterns. We introduce two ancient genes, SKL1 and SKL2, present in all higher plant groups that were previously overlooked due to their overall similarity to the ancestral SKs from which they originated. SKL1 mutants in the model plant Arabidopsis indicate this gene is required for chloroplast biogenesis. We show that SKL2 acquired a protein–protein interaction domain that is evolving under positive selection. We also show that SK duplicates that retained their ancestral enzyme function have acquired new expression patterns correlated with developmental processes and stress responses. These findings demonstrate that plant SK evolution has played an important role in both the acquisition of novel gene function as well as the diversification of metabolic regulation.
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Affiliation(s)
- Geoffrey Fucile
- Department of Cell and Systems Biology, University of Toronto, Canada
| | - Shannon Falconer
- Department of Cell and Systems Biology, University of Toronto, Canada
| | - Dinesh Christendat
- Department of Cell and Systems Biology, University of Toronto, Canada
- * E-mail:
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Christin PA, Salamin N, Muasya AM, Roalson EH, Russier F, Besnard G. Evolutionary switch and genetic convergence on rbcL following the evolution of C4 photosynthesis. Mol Biol Evol 2008; 25:2361-8. [PMID: 18695049 DOI: 10.1093/molbev/msn178] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Rubisco is responsible for the fixation of CO2 into organic compounds through photosynthesis and thus has a great agronomic importance. It is well established that this enzyme suffers from a slow catalysis, and its low specificity results into photorespiration, which is considered as an energy waste for the plant. However, natural variations exist, and some Rubisco lineages, such as in C4 plants, exhibit higher catalytic efficiencies coupled to lower specificities. These C4 kinetics could have evolved as an adaptation to the higher CO2 concentration present in C4 photosynthetic cells. In this study, using phylogenetic analyses on a large data set of C3 and C4 monocots, we showed that the rbcL gene, which encodes the large subunit of Rubisco, evolved under positive selection in independent C4 lineages. This confirms that selective pressures on Rubisco have been switched in C4 plants by the high CO2 environment prevailing in their photosynthetic cells. Eight rbcL codons evolving under positive selection in C4 clades were involved in parallel changes among the 23 independent monocot C4 lineages included in this study. These amino acids are potentially responsible for the C4 kinetics, and their identification opens new roads for human-directed Rubisco engineering. The introgression of C4-like high-efficiency Rubisco would strongly enhance C3 crop yields in the future CO2-enriched atmosphere.
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Sambatti JBM, Ortiz-Barrientos D, Baack EJ, Rieseberg LH. Ecological selection maintains cytonuclear incompatibilities in hybridizing sunflowers. Ecol Lett 2008; 11:1082-91. [PMID: 18643842 DOI: 10.1111/j.1461-0248.2008.01224.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Despite the recent renaissance in studies of ecological speciation, the connection between ecological selection and the evolution of reproductive isolation remains tenuous. We tested whether habitat adaptation of cytoplasmic genomes contributes to the maintenance of reproductive barriers in hybridizing sunflower species, Helianthus annuus and Helianthus petiolaris. We transplanted genotypes of the parental species, reciprocal F1 hybrids and all eight possible backcross combinations of nuclear and cytoplasmic genomes into the contrasting xeric and mesic habitats of the parental species. Analysis of survivorship across two growing seasons revealed that the parental species' cytoplasms were strongly locally adapted and that cytonuclear interactions (CNIs) significantly affected the fitness and architecture of hybrid plants. A significant fraction of the CNIs have transgenerational effects, perhaps due to divergence in imprinting patterns. Our results suggest a common means by which ecological selection may contribute to speciation and have significant implications for the persistence of hybridizing species.
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Affiliation(s)
- Julianno B M Sambatti
- Department of Botany, University of British Columbia, 3529-6270 University Blvd., Vancouver, BC, Canada V6T1Z4
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Erixon P, Oxelman B. Whole-gene positive selection, elevated synonymous substitution rates, duplication, and indel evolution of the chloroplast clpP1 gene. PLoS One 2008; 3:e1386. [PMID: 18167545 PMCID: PMC2148103 DOI: 10.1371/journal.pone.0001386] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Accepted: 12/05/2007] [Indexed: 11/27/2022] Open
Abstract
Background Synonymous DNA substitution rates in the plant chloroplast genome are generally relatively slow and lineage dependent. Non-synonymous rates are usually even slower due to purifying selection acting on the genes. Positive selection is expected to speed up non-synonymous substitution rates, whereas synonymous rates are expected to be unaffected. Until recently, positive selection has seldom been observed in chloroplast genes, and large-scale structural rearrangements leading to gene duplications are hitherto supposed to be rare. Methodology/Principle Findings We found high substitution rates in the exons of the plastid clpP1 gene in Oenothera (the Evening Primrose family) and three separate lineages in the tribe Sileneae (Caryophyllaceae, the Carnation family). Introns have been lost in some of the lineages, but where present, the intron sequences have substitution rates similar to those found in other introns of their genomes. The elevated substitution rates of clpP1 are associated with statistically significant whole-gene positive selection in three branches of the phylogeny. In two of the lineages we found multiple copies of the gene. Neighboring genes present in the duplicated fragments do not show signs of elevated substitution rates or positive selection. Although non-synonymous substitutions account for most of the increase in substitution rates, synonymous rates are also markedly elevated in some lineages. Whereas plant clpP1 genes experiencing negative (purifying) selection are characterized by having very conserved lengths, genes under positive selection often have large insertions of more or less repetitive amino acid sequence motifs. Conclusions/Significance We found positive selection of the clpP1 gene in various plant lineages to correlated with repeated duplication of the clpP1 gene and surrounding regions, repetitive amino acid sequences, and increase in synonymous substitution rates. The present study sheds light on the controversial issue of whether negative or positive selection is to be expected after gene duplications by providing evidence for the latter alternative. The observed increase in synonymous substitution rates in some of the lineages indicates that the detection of positive selection may be obscured under such circumstances. Future studies are required to explore the functional significance of the large inserted repeated amino acid motifs, as well as the possibility that synonymous substitution rates may be affected by positive selection.
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Affiliation(s)
- Per Erixon
- Department of Systematic Botany, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
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Muir G, Filatov D. A selective sweep in the chloroplast DNA of dioecious silene (section Elisanthe). Genetics 2007; 177:1239-47. [PMID: 17660574 PMCID: PMC2034629 DOI: 10.1534/genetics.107.071969] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gene flow occurs predominantly via pollen in angiosperms, leading to stronger population subdivision for maternally inherited markers, relative to paternally or biparentally inherited genes. In contrast to this trend, population subdivision within Silene latifolia and S. dioica, as well as subdivision between the two species, is substantially lower in maternally inherited chloroplast genes compared to paternally inherited Y-linked genes. A significant frequency spectrum bias toward rare polymorphisms and a significant loss of polymorphism in chloroplast genes compared to Y-linked and autosomal genes suggest that intra- and inter-specific subdivision in the chloroplast DNA may have been eroded by a selective sweep that has crossed the S. latifolia and S. dioica species boundary.
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Affiliation(s)
- Graham Muir
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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Kapralov MV, Filatov DA. Widespread positive selection in the photosynthetic Rubisco enzyme. BMC Evol Biol 2007; 7:73. [PMID: 17498284 PMCID: PMC1884142 DOI: 10.1186/1471-2148-7-73] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 05/11/2007] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Rubisco enzyme catalyzes the first step in net photosynthetic CO2 assimilation and photorespiratory carbon oxidation and is responsible for almost all carbon fixation on Earth. The large subunit of Rubisco is encoded by the chloroplast rbcL gene, which is widely used for reconstruction of plant phylogenies due to its conservative nature. Plant systematicists have mainly used rbcL paying little attention to its function, and the question whether it evolves under Darwinian selection has received little attention. The purpose of our study was to evaluate how common is positive selection in Rubisco among the phototrophs and where in the Rubisco structure does positive selection occur. RESULTS We searched for positive selection in rbcL sequences from over 3000 species representing all lineages of green plants and some lineages of other phototrophs, such as brown and red algae, diatoms, euglenids and cyanobacteria. Our molecular phylogenetic analysis found the presence of positive selection in rbcL of most analyzed land plants, but not in algae and cyanobacteria. The mapping of the positively selected residues on the Rubisco tertiary structure revealed that they are located in regions important for dimer-dimer, intradimer, large subunit-small subunit and Rubisco-Rubisco activase interactions, and that some of the positively selected residues are close to the active site. CONCLUSION Our results demonstrate that despite its conservative nature, Rubisco evolves under positive selection in most lineages of land plants, and after billions of years of evolution Darwinian selection still fine-tunes its performance. Widespread positive selection in rbcL has to be taken into account when this gene is used for phylogenetic reconstructions.
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Affiliation(s)
- Maxim V Kapralov
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Dmitry A Filatov
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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