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Folk RA, Charboneau JLM, Belitz M, Singh T, Kates HR, Soltis DE, Soltis PS, Guralnick RP, Siniscalchi CM. Anatomy of a mega-radiation: Biogeography and niche evolution in Astragalus. Am J Bot 2024; 111:e16299. [PMID: 38419145 DOI: 10.1002/ajb2.16299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 03/02/2024]
Abstract
PREMISE Astragalus (Fabaceae), with more than 3000 species, represents a globally successful radiation of morphologically highly similar species predominant across the northern hemisphere. It has attracted attention from systematists and biogeographers, who have asked what factors might be behind the extraordinary diversity of this important arid-adapted clade and what sets it apart from close relatives with far less species richness. METHODS Here, for the first time using extensive phylogenetic sampling, we asked whether (1) Astragalus is uniquely characterized by bursts of radiation or whether diversification instead is uniform and no different from closely related taxa. Then we tested whether the species diversity of Astragalus is attributable specifically to its predilection for (2) cold and arid habitats, (3) particular soils, or to (4) chromosome evolution. Finally, we tested (5) whether Astragalus originated in central Asia as proposed and (6) whether niche evolutionary shifts were subsequently associated with the colonization of other continents. RESULTS Our results point to the importance of heterogeneity in the diversification of Astragalus, with upshifts associated with the earliest divergences but not strongly tied to any abiotic factor or biogeographic regionalization tested here. The only potential correlate with diversification we identified was chromosome number. Biogeographic shifts have a strong association with the abiotic environment and highlight the importance of central Asia as a biogeographic gateway. CONCLUSIONS Our investigation shows the importance of phylogenetic and evolutionary studies of logistically challenging "mega-radiations." Our findings reject any simple key innovation behind high diversity and underline the often nuanced, multifactorial processes leading to species-rich clades.
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Affiliation(s)
- Ryan A Folk
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Joseph L M Charboneau
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Michael Belitz
- Florida Museum, University of Florida, Gainesville, FL, USA
| | - Tajinder Singh
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | | | - Douglas E Soltis
- Florida Museum, University of Florida, Gainesville, FL, USA
- Genetics Institute, University of Florida, Gainesville, FL, USA
- Biodiversity Institute, University of Florida, Gainesville, FL, USA
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Pamela S Soltis
- Florida Museum, University of Florida, Gainesville, FL, USA
- Genetics Institute, University of Florida, Gainesville, FL, USA
- Biodiversity Institute, University of Florida, Gainesville, FL, USA
| | - Robert P Guralnick
- Florida Museum, University of Florida, Gainesville, FL, USA
- Biodiversity Institute, University of Florida, Gainesville, FL, USA
| | - Carolina M Siniscalchi
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
- General Libraries, Mississippi State University, Mississippi State, MS, USA
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2
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Li YL, Nie LY, Deng SW, Duan L, Wang ZF, Charboneau JLM, Ho BC, Chen HF. Characterization of Firmiana danxiaensis plastomes and comparative analysis of Firmiana: insight into its phylogeny and evolution. BMC Genomics 2024; 25:203. [PMID: 38389079 PMCID: PMC10885454 DOI: 10.1186/s12864-024-10046-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/24/2024] [Indexed: 02/24/2024] Open
Abstract
BACKGROUND Firmiana danxiaensis is a critically endangered and ecologically important tree currently only found in four locations in Danxia or Karst habitats in northern Guangdong Province, China. The specialized habitat preference makes it an ideal model species for study of adaptive evolution. Meanwhile, the phylogenetic relationships of F. danxiaensis in four locations under two landforms are unclear. Therefore, we sequenced its complete chloroplast (cp.) genomes and conducted comprehensive interspecific and intrageneric plastome studies. RESULTS The F. danxiaensis plastomes in four locations showed a typical quadripartite and circular structure that ranged from 160,832 to 161,206 bp in size, with 112 unique genes encoded. Comparative genomics showed that the plastomes of F. danxiaensis were relatively conserved with high similarity of genome organization, gene number, GC content and SSRs. While the genomes revealed higher biased codon preferences in Karst habitat than those in Danxia habitats. Eighteen and 11 divergent hotpots were identified at interspecific and intrageneric levels for species identification and further phylogenetic studies. Seven genes (clpP, accD, ccsA, ndhH, rpl20, rpoC2, and rps4) were under positive selection and may be related to adaptation. Phylogenetic analysis revealed that F. danxiaensis is sister to F. major and F. simplex. However, the interspecific relationships are not consistent with the habitat types. CONCLUSIONS The characteristics and interspecific relationship of F. danxiaensis plastomes provide new insights into further integration of geographical factors, environmental factors, and genetic variations on the genomic study of F. danxiaensis. Together, our study will contribute to the study of species identification, population genetics, and conservation biology of F. danxiaensis.
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Affiliation(s)
- Ya-Li Li
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Li-Yun Nie
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuang-Wen Deng
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lei Duan
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Zheng-Feng Wang
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 510650, China
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Key Laboratory of Carbon Sequestration in Terrestrial Ecosystem, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Joseph L M Charboneau
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Boon-Chuan Ho
- Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, Singapore, 259569, Republic of Singapore
| | - Hong-Feng Chen
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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3
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Peláez JN, Gloss AD, Goldman-Huertas B, Kim B, Lapoint RT, Pimentel-Solorio G, Verster KI, Aguilar JM, Nelson Dittrich AC, Singhal M, Suzuki HC, Matsunaga T, Armstrong EE, Charboneau JLM, Groen SC, Hembry DH, Ochoa CJ, O’Connor TK, Prost S, Zaaijer S, Nabity PD, Wang J, Rodas E, Liang I, Whiteman NK. Evolution of chemosensory and detoxification gene families across herbivorous Drosophilidae. G3 (Bethesda) 2023; 13:jkad133. [PMID: 37317982 PMCID: PMC10411586 DOI: 10.1093/g3journal/jkad133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 03/19/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023]
Abstract
Herbivorous insects are exceptionally diverse, accounting for a quarter of all known eukaryotic species, but the genomic basis of adaptations that enabled this dietary transition remains poorly understood. Many studies have suggested that expansions and contractions of chemosensory and detoxification gene families-genes directly mediating interactions with plant chemical defenses-underlie successful plant colonization. However, this hypothesis has been challenging to test because the origins of herbivory in many insect lineages are ancient (>150 million years ago (mya)), obscuring genomic evolutionary patterns. Here, we characterized chemosensory and detoxification gene family evolution across Scaptomyza, a genus nested within Drosophila that includes a recently derived (<15 mya) herbivore lineage of mustard (Brassicales) specialists and carnation (Caryophyllaceae) specialists, and several nonherbivorous species. Comparative genomic analyses revealed that herbivorous Scaptomyza has among the smallest chemosensory and detoxification gene repertoires across 12 drosophilid species surveyed. Rates of gene turnover averaged across the herbivore clade were significantly higher than background rates in over half of the surveyed gene families. However, gene turnover was more limited along the ancestral herbivore branch, with only gustatory receptors and odorant-binding proteins experiencing strong losses. The genes most significantly impacted by gene loss, duplication, or changes in selective constraint were those involved in detecting compounds associated with feeding on living plants (bitter or electrophilic phytotoxins) or their ancestral diet (fermenting plant volatiles). These results provide insight into the molecular and evolutionary mechanisms of plant-feeding adaptations and highlight gene candidates that have also been linked to other dietary transitions in Drosophila.
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Affiliation(s)
- Julianne N Peláez
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Andrew D Gloss
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Benjamin Goldman-Huertas
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Bernard Kim
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Richard T Lapoint
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | | | - Kirsten I Verster
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Jessica M Aguilar
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Anna C Nelson Dittrich
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Boyce Thompson Institute, Cornell University, Ithaca, NY 14853, USA
| | - Malvika Singhal
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Chemistry & Biochemistry, University of Oregon, Eugene, OR 97403, USA
| | - Hiromu C Suzuki
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Teruyuki Matsunaga
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Ellie E Armstrong
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Joseph L M Charboneau
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Simon C Groen
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
- Department of Nematology, University of California Riverside, Riverside, CA 92521, USA
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 92521, USA
- Center for Plant Cell Biology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA
| | - David H Hembry
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biology, University of Texas Permian Basin, Odessa, TX 79762, USA
| | - Christopher J Ochoa
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Timothy K O’Connor
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Stefan Prost
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Sophie Zaaijer
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Jacobs Institute, Cornell Tech, New York, NY 10044, USA
- FIND Genomics, New York, NY 10044, USA
| | - Paul D Nabity
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 92521, USA
| | - Jiarui Wang
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90007, USA
| | - Esteban Rodas
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Irene Liang
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Noah K Whiteman
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
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4
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Peláez JN, Gloss AD, Ray JF, Chaturvedi S, Haji D, Charboneau JLM, Verster KI, Whiteman NK. Evolution and genomic basis of the plant-penetrating ovipositor: a key morphological trait in herbivorous Drosophilidae. Proc Biol Sci 2022; 289:20221938. [PMID: 36350206 PMCID: PMC9653217 DOI: 10.1098/rspb.2022.1938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Herbivorous insects are extraordinarily diverse, yet are found in only one-third of insect orders. This skew may result from barriers to plant colonization, coupled with phylogenetic constraint on plant-colonizing adaptations. The plant-penetrating ovipositor, however, is one trait that surmounts host plant physical defences and may be evolutionarily labile. Ovipositors densely lined with hard bristles have evolved repeatedly in herbivorous lineages, including within the Drosophilidae. However, the evolution and genetic basis of this innovation has not been well studied. Here, we focused on the evolution of this trait in Scaptomyza, a genus sister to Hawaiian Drosophila, that contains a herbivorous clade. Our phylogenetic approach revealed that ovipositor bristle number increased as herbivory evolved in the Scaptomyza lineage. Through a genome-wide association study, we then dissected the genomic architecture of variation in ovipositor bristle number within S. flava. Top-associated variants were enriched for transcriptional repressors, and the strongest associations included genes contributing to peripheral nervous system development. Individual genotyping supported the association at a variant upstream of Gαi, a neural development gene, contributing to a gain of 0.58 bristles/major allele. These results suggest that regulatory variation involving conserved developmental genes contributes to this key morphological trait involved in plant colonization.
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Affiliation(s)
- Julianne N. Peláez
- Department of Integrative Biology, University of California, Berkeley, 94720 CA, USA
| | - Andrew D. Gloss
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, NY 10012, USA,Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Julianne F. Ray
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Samridhi Chaturvedi
- Department of Integrative Biology, University of California, Berkeley, 94720 CA, USA
| | - Diler Haji
- Department of Integrative Biology, University of California, Berkeley, 94720 CA, USA
| | | | - Kirsten I. Verster
- Department of Integrative Biology, University of California, Berkeley, 94720 CA, USA
| | - Noah K. Whiteman
- Department of Integrative Biology, University of California, Berkeley, 94720 CA, USA,Department of Molecular and Cell Biology, University of California, Berkeley, 94720 CA, USA
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5
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Charboneau JLM, Cronn RC, Liston A, Wojciechowski MF, Sanderson MJ. Plastome Structural Evolution and Homoplastic Inversions in Neo-Astragalus (Fabaceae). Genome Biol Evol 2021; 13:evab215. [PMID: 34534296 PMCID: PMC8486006 DOI: 10.1093/gbe/evab215] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2021] [Indexed: 12/23/2022] Open
Abstract
The plastid genomes of photosynthetic green plants have largely maintained conserved gene content and order as well as structure over hundreds of millions of years of evolution. Several plant lineages, however, have departed from this conservation and contain many plastome structural rearrangements, which have been associated with an abundance of repeated sequences both overall and near rearrangement endpoints. We sequenced the plastomes of 25 taxa of Astragalus L. (Fabaceae), a large genus in the inverted repeat-lacking clade of legumes, to gain a greater understanding of the connection between repeats and plastome inversions. We found plastome repeat structure has a strong phylogenetic signal among these closely related taxa mostly in the New World clade of Astragalus called Neo-Astragalus. Taxa without inversions also do not differ substantially in their overall repeat structure from four taxa each with one large-scale inversion. For two taxa with inversion endpoints between the same pairs of genes, differences in their exact endpoints indicate the inversions occurred independently. Our proposed mechanism for inversion formation suggests the short inverted repeats now found near the endpoints of the four inversions may be there as a result of these inversions rather than their cause. The longer inverted repeats now near endpoints may have allowed the inversions first mediated by shorter microhomologous sequences to propagate, something that should be considered in explaining how any plastome rearrangement becomes fixed regardless of the mechanism of initial formation.
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Affiliation(s)
- Joseph L M Charboneau
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, USA
| | - Richard C Cronn
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, Oregon, USA
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | | | - Michael J Sanderson
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, USA
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Copetti D, Búrquez A, Bustamante E, Charboneau JLM, Childs KL, Eguiarte LE, Lee S, Liu TL, McMahon MM, Whiteman NK, Wing RA, Wojciechowski MF, Sanderson MJ. Extensive gene tree discordance and hemiplasy shaped the genomes of North American columnar cacti. Proc Natl Acad Sci U S A 2017; 114:12003-12008. [PMID: 29078296 PMCID: PMC5692538 DOI: 10.1073/pnas.1706367114] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Few clades of plants have proven as difficult to classify as cacti. One explanation may be an unusually high level of convergent and parallel evolution (homoplasy). To evaluate support for this phylogenetic hypothesis at the molecular level, we sequenced the genomes of four cacti in the especially problematic tribe Pachycereeae, which contains most of the large columnar cacti of Mexico and adjacent areas, including the iconic saguaro cactus (Carnegiea gigantea) of the Sonoran Desert. We assembled a high-coverage draft genome for saguaro and lower coverage genomes for three other genera of tribe Pachycereeae (Pachycereus, Lophocereus, and Stenocereus) and a more distant outgroup cactus, Pereskia We used these to construct 4,436 orthologous gene alignments. Species tree inference consistently returned the same phylogeny, but gene tree discordance was high: 37% of gene trees having at least 90% bootstrap support conflicted with the species tree. Evidently, discordance is a product of long generation times and moderately large effective population sizes, leading to extensive incomplete lineage sorting (ILS). In the best supported gene trees, 58% of apparent homoplasy at amino sites in the species tree is due to gene tree-species tree discordance rather than parallel substitutions in the gene trees themselves, a phenomenon termed "hemiplasy." The high rate of genomic hemiplasy may contribute to apparent parallelisms in phenotypic traits, which could confound understanding of species relationships and character evolution in cacti.
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Affiliation(s)
- Dario Copetti
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ 85721
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Alberto Búrquez
- Instituto de Ecología, Unidad Hermosillo, Universidad Nacional Autónoma de México, Hermosillo, Sonora, Mexico
| | - Enriquena Bustamante
- Instituto de Ecología, Unidad Hermosillo, Universidad Nacional Autónoma de México, Hermosillo, Sonora, Mexico
| | - Joseph L M Charboneau
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721
| | - Kevin L Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | - Luis E Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Seunghee Lee
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ 85721
| | - Tiffany L Liu
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | | | - Noah K Whiteman
- Department of Integrative Biology, University of California, Berkeley, CA 94720
| | - Rod A Wing
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ 85721
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | | | - Michael J Sanderson
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721;
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7
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Sanderson MJ, Copetti D, Búrquez A, Bustamante E, Charboneau JLM, Eguiarte LE, Kumar S, Lee HO, Lee J, McMahon M, Steele K, Wing R, Yang TJ, Zwickl D, Wojciechowski MF. Exceptional reduction of the plastid genome of saguaro cactus (Carnegiea gigantea): Loss of the ndh gene suite and inverted repeat. Am J Bot 2015; 102:1115-1127. [PMID: 26199368 DOI: 10.3732/ajb.1500184] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 06/18/2015] [Indexed: 05/21/2023]
Abstract
UNLABELLED • PREMISE OF THE STUDY Land-plant plastid genomes have only rarely undergone significant changes in gene content and order. Thus, discovery of additional examples adds power to tests for causes of such genome-scale structural changes.• METHODS Using next-generation sequence data, we assembled the plastid genome of saguaro cactus and probed the nuclear genome for transferred plastid genes and functionally related nuclear genes. We combined these results with available data across Cactaceae and seed plants more broadly to infer the history of gene loss and to assess the strength of phylogenetic association between gene loss and loss of the inverted repeat (IR).• KEY RESULTS The saguaro plastid genome is the smallest known for an obligately photosynthetic angiosperm (∼113 kb), having lost the IR and plastid ndh genes. This loss supports a statistically strong association across seed plants between the loss of ndh genes and the loss of the IR. Many nonplastid copies of plastid ndh genes were found in the nuclear genome, but none had intact reading frames; nor did three related nuclear-encoded subunits. However, nuclear pgr5, which functions in a partially redundant pathway, was intact.• CONCLUSIONS The existence of an alternative pathway redundant with the function of the plastid NADH dehydrogenase-like complex (NDH) complex may permit loss of the plastid ndh gene suite in photoautotrophs like saguaro. Loss of these genes may be a recurring mechanism for overall plastid genome size reduction, especially in combination with loss of the IR.
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Affiliation(s)
- Michael J Sanderson
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721 USA
| | - Dario Copetti
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721 USA International Rice Research Institute, Genetic Resource Center, Los Baños, Laguna, Philippines
| | - Alberto Búrquez
- Instituto de Ecologia, Unidad Hermosillo, UNAM, Hermosillo, Sonora, Mexico
| | | | - Joseph L M Charboneau
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721 USA
| | | | - Sudhir Kumar
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, Pennsylvania 19122 USA
| | - Hyun Oh Lee
- Phyzen Genomics Institute, 501-1, Gwanak Century Tower, Gwanak-gu, Seoul, 151-836, Republic of Korea
| | - Junki Lee
- Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea
| | - Michelle McMahon
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721 USA
| | - Kelly Steele
- Faculty of Science and Mathematics, College of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 USA
| | - Rod Wing
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721 USA International Rice Research Institute, Genetic Resource Center, Los Baños, Laguna, Philippines
| | - Tae-Jin Yang
- Faculty of Science and Mathematics, College of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 USA
| | - Derrick Zwickl
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721 USA
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