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Barrett CF, Pace MC, Corbett CW. Plastid genome evolution in leafless members of the orchid subfamily Orchidoideae, with a focus on Degranvillea dermaptera. AMERICAN JOURNAL OF BOTANY 2024; 111:e16370. [PMID: 38989916 DOI: 10.1002/ajb2.16370] [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: 11/03/2023] [Revised: 04/25/2024] [Accepted: 04/25/2024] [Indexed: 07/12/2024]
Abstract
PREMISE Leafless, heterotrophic plants are prime examples of organismal modification, the genomic consequences of which have received considerable interest. In particular, plastid genomes (plastomes) are being sequenced at a high rate, allowing continual refinement of conceptual models of reductive evolution in heterotrophs. However, numerous sampling gaps exist, hindering the ability to conduct comprehensive phylogenomic analyses in these plants. METHODS Using floral tissue from an herbarium specimen, we sequenced and analyzed the plastome of Degranvillea dermaptera, a rarely collected, leafless orchid species from South America about which little is known, including its phylogenetic affinities. RESULTS The plastome is the most reduced of those sequenced among the orchid subfamily Orchidoideae. In Degranvillea, it has lost the majority of genes found in leafy autotrophic species, is structurally rearranged, and has similar gene content to the most reduced plastomes among the orchids. We found strong evidence for the placement of Degranvillea within the subtribe Spiranthinae using models that explicitly account for heterotachy, or lineage-specific evolutionary rate variation over time. We further found evidence of relaxed selection on several genes and of correlations among substitution rates and several other "traits" of the plastome among leafless members of orchid subfamily Orchidoideae. CONCLUSIONS Our findings advance knowledge on the phylogenetic relationships and paths of plastid genome evolution among the orchids, which have experienced more independent transitions to heterotrophy than any other plant family. This study demonstrates the importance of herbarium collections in comparative genomics of poorly known species of conservation concern.
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Affiliation(s)
- Craig F Barrett
- Department of Biology, West Virginia University, 53 Campus Drive, Morgantown, 26506, WV, USA
| | - Matthew C Pace
- New York Botanical Garden, 2900 Southern Boulevard, Bronx, 10458, NY, USA
| | - Cameron W Corbett
- Department of Biology, West Virginia University, 53 Campus Drive, Morgantown, 26506, WV, USA
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Muti RM, Barrett CF, Sinn BT. Evolution of Whirly1 in the angiosperms: sequence, splicing, and expression in a clade of early transitional mycoheterotrophic orchids. FRONTIERS IN PLANT SCIENCE 2024; 15:1241515. [PMID: 39006962 PMCID: PMC11239579 DOI: 10.3389/fpls.2024.1241515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 06/07/2024] [Indexed: 07/16/2024]
Abstract
The plastid-targeted transcription factor Whirly1 (WHY1) has been implicated in chloroplast biogenesis, plastid genome stability, and fungal defense response, which together represent characteristics of interest for the study of autotrophic losses across the angiosperms. While gene loss in the plastid and nuclear genomes has been well studied in mycoheterotrophic plants, the evolution of the molecular mechanisms impacting genome stability is completely unknown. Here, we characterize the evolution of WHY1 in four early transitional mycoheterotrophic orchid species in the genus Corallorhiza by synthesizing the results of phylogenetic, transcriptomic, and comparative genomic analyses with WHY1 genomic sequences sampled from 21 orders of angiosperms. We found an increased number of non-canonical WHY1 isoforms assembled from all but the greenest Corallorhiza species, including intron retention in some isoforms. Within Corallorhiza, phylotranscriptomic analyses revealed the presence of tissue-specific differential expression of WHY1 in only the most photosynthetically capable species and a coincident increase in the number of non-canonical WHY1 isoforms assembled from fully mycoheterotrophic species. Gene- and codon-level tests of WHY1 selective regimes did not infer significant signal of either relaxed selection or episodic diversifying selection in Corallorhiza but did so for relaxed selection in the late-stage full mycoheterotrophic orchids Epipogium aphyllum and Gastrodia elata. Additionally, nucleotide substitutions that most likely impact the function of WHY1, such as nonsense mutations, were only observed in late-stage mycoheterotrophs. We propose that our findings suggest that splicing and expression changes may precede the selective shifts we inferred for late-stage mycoheterotrophic species, which therefore does not support a primary role for WHY1 in the transition to mycoheterotrophy in the Orchidaceae. Taken together, this study provides the most comprehensive view of WHY1 evolution across the angiosperms to date.
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Affiliation(s)
- Rachel M. Muti
- Department of Biology and Earth Science, Otterbein University, Westerville, OH, United States
- Department of Hematology and Medical Oncology, Emory University, Atlanta, GA, United States
| | - Craig F. Barrett
- Department of Biology, West Virginia University, Morgantown, WV, United States
| | - Brandon T. Sinn
- Department of Biology and Earth Science, Otterbein University, Westerville, OH, United States
- Faculty of Biology, University of Latvia, Riga, Latvia
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Samigullin TH, Logacheva MD, Averyanov LV, Zeng SJ, Fu LF, Nuraliev MS. Phylogenetic position and plastid genome structure of Vietorchis, a mycoheterotrophic genus of Orchidaceae (subtribe Orchidinae) endemic to Vietnam. FRONTIERS IN PLANT SCIENCE 2024; 15:1393225. [PMID: 38855461 PMCID: PMC11157612 DOI: 10.3389/fpls.2024.1393225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 04/12/2024] [Indexed: 06/11/2024]
Abstract
The orchid genus Vietorchis comprises three species, all discovered in the 21 century. Each of these species is achlorophyllous, mycoheterotrophic and is known to be endemic to Vietnam. The type species of the genus, V. aurea, occurs in a single location in northern Vietnam within a lowland limestone karstic area. Vietorchis furcata and V. proboscidea, in contrast, are confined to mountains of southern Vietnam, far away from any limestone formations. Taxonomic placement of Vietorchis remained uncertain for the reason of inconclusive morphological affinities. At the same time, the genus has never been included into molecular phylogenetic studies. We investigate the phylogenetic relationships of two species of Vietorchis (V. aurea and V. furcata) based on three DNA datasets: (1) a dataset comprising two nuclear regions, (2) a dataset comprising two plastid regions, and (3) a dataset employing data on the entire plastid genomes. Our phylogenetic reconstructions support the placement of Vietorchis into the subtribe Orchidinae (tribe Orchideae, subfamily Orchidoideae). This leads to a conclusion that the previously highlighted similarities in the rhizome morphology between Vietorchis and certain mycoheterotrophic genera of the subfamilies Epidendroideae and Vanilloideae are examples of a convergence. Vietorchis is deeply nested within Orchidinae, and therefore the subtribe Vietorchidinae is to be treated as a synonym of Orchidinae. In the obtained phylogenetic reconstructions, Vietorchis is sister to the photosynthetic genus Sirindhornia. Sirindhornia is restricted to limestone mountains, which allows to speculate that association with limestone karst is plesiomorphic for Vietorchis. Flower morphology is concordant with the molecular data in placing Vietorchis into Orchidinae and strongly supports the assignment of the genus to one of the two major clades within this subtribe. Within this clade, however, Vietorchis shows no close structural similarity with any of its genera; in particular, the proximity between Vietorchis and Sirindhornia has never been proposed. Finally, we assembled the plastid genome of V. furcata, which is 65969 bp long and contains 45 unique genes, being one of the most reduced plastomes in the subfamily Orchidoideae. The plastome of Vietorchis lacks any rearrangements in comparison with the closest studied autotrophic species, and possesses substantially contracted inverted repeats. No signs of positive selection acting on the protein-coding plastid sequences were detected.
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Affiliation(s)
- Tahir H. Samigullin
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Maria D. Logacheva
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
- Center for Molecular and Cellular Biology, Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Leonid V. Averyanov
- Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Si-Jin Zeng
- State Key Laboratory of Plant Diversity and Specialty Crops / Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China and South China National Botanical Garden, Guangzhou, China
| | - Long-Fei Fu
- Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, China
| | - Maxim S. Nuraliev
- Department of Higher Plants, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
- Joint Russian-Vietnamese Tropical Scientific and Technological Center, Hanoi, Vietnam
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Sanchez-Puerta MV, Ceriotti LF, Gatica-Soria LM, Roulet ME, Garcia LE, Sato HA. Invited Review Beyond parasitic convergence: unravelling the evolution of the organellar genomes in holoparasites. ANNALS OF BOTANY 2023; 132:909-928. [PMID: 37503831 PMCID: PMC10808021 DOI: 10.1093/aob/mcad108] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/27/2023] [Indexed: 07/29/2023]
Abstract
BACKGROUND The molecular evolution of organellar genomes in angiosperms has been studied extensively, with some lineages, such as parasitic ones, displaying unique characteristics. Parasitism has emerged 12 times independently in angiosperm evolution. Holoparasitism is the most severe form of parasitism, and is found in ~10 % of parasitic angiosperms. Although a few holoparasitic species have been examined at the molecular level, most reports involve plastomes instead of mitogenomes. Parasitic plants establish vascular connections with their hosts through haustoria to obtain water and nutrients, which facilitates the exchange of genetic information, making them more susceptible to horizontal gene transfer (HGT). HGT is more prevalent in the mitochondria than in the chloroplast or nuclear compartments. SCOPE This review summarizes current knowledge on the plastid and mitochondrial genomes of holoparasitic angiosperms, compares the genomic features across the different lineages, and discusses their convergent evolutionary trajectories and distinctive features. We focused on Balanophoraceae (Santalales), which exhibits extraordinary traits in both their organelles. CONCLUSIONS Apart from morphological similarities, plastid genomes of holoparasitic plants also display other convergent features, such as rampant gene loss, biased nucleotide composition and accelerated evolutionary rates. In addition, the plastomes of Balanophoraceae have extremely low GC and gene content, and two unexpected changes in the genetic code. Limited data on the mitochondrial genomes of holoparasitic plants preclude thorough comparisons. Nonetheless, no obvious genomic features distinguish them from the mitochondria of free-living angiosperms, except for a higher incidence of HGT. HGT appears to be predominant in holoparasitic angiosperms with a long-lasting endophytic stage. Among the Balanophoraceae, mitochondrial genomes exhibit disparate evolutionary paths with notable levels of heteroplasmy in Rhopalocnemis and unprecedented levels of HGT in Lophophytum. Despite their differences, these Balanophoraceae share a multichromosomal mitogenome, a feature also found in a few free-living angiosperms.
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Affiliation(s)
- M Virginia Sanchez-Puerta
- IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, Chacras de Coria, M5528AHB, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Padre Jorge Contreras 1300, Universidad Nacional de Cuyo, M5502JMA, Mendoza, Argentina
| | - Luis F Ceriotti
- IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, Chacras de Coria, M5528AHB, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Padre Jorge Contreras 1300, Universidad Nacional de Cuyo, M5502JMA, Mendoza, Argentina
| | - Leonardo M Gatica-Soria
- IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, Chacras de Coria, M5528AHB, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Padre Jorge Contreras 1300, Universidad Nacional de Cuyo, M5502JMA, Mendoza, Argentina
| | - M Emilia Roulet
- IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, Chacras de Coria, M5528AHB, Mendoza, Argentina
| | - Laura E Garcia
- IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, Chacras de Coria, M5528AHB, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Padre Jorge Contreras 1300, Universidad Nacional de Cuyo, M5502JMA, Mendoza, Argentina
| | - Hector A Sato
- Facultad de Ciencias Agrarias, Cátedra de Botánica General–Herbario JUA, Alberdi 47, Universidad Nacional de Jujuy, 4600 Jujuy, Argentina
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Niu Z, Lin Z, Tong Y, Chen X, Deng Y. Complete plastid genome structure of 13 Asian Justicia (Acanthaceae) species: comparative genomics and phylogenetic analyses. BMC PLANT BIOLOGY 2023; 23:564. [PMID: 37964203 PMCID: PMC10647099 DOI: 10.1186/s12870-023-04532-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 10/17/2023] [Indexed: 11/16/2023]
Abstract
BACKGROUND Justicia L. is the largest genus in Acanthaceae Juss. and widely distributed in tropical and subtropical regions of the world. Previous phylogenetic studies have proposed a general phylogenetic framework for Justicia based on several molecular markers. However, their studies were mainly focused on resolution of phylogenetic issues of Justicia in Africa, Australia and South America due to limited sampling from Asia. Additionally, although Justicia plants are of high medical and ornamental values, little research on its genetics was reported. Therefore, to improve the understanding of its genomic structure and relationships among Asian Justicia plants, we sequenced complete chloroplast (cp.) genomes of 12 Asian plants and combined with the previously published cp. genome of Justicia leptostachya Hemsl. for further comparative genomics and phylogenetic analyses. RESULTS All the cp. genomes exhibit a typical quadripartite structure without genomic rearrangement and gene loss. Their sizes range from 148,374 to 151,739 bp, including a large single copy (LSC, 81,434-83,676 bp), a small single copy (SSC, 16,833-17,507 bp) and two inverted repeats (IR, 24,947-25,549 bp). GC contents range from 38.1 to 38.4%. All the plastomes contain 114 genes, including 80 protein-coding genes, 30 tRNAs and 4 rRNAs. IR variation and repetitive sequences analyses both indicated that Justicia grossa C. B. Clarke is different from other Justicia species because its lengths of ndhF and ycf1 in IRs are shorter than others and it is richest in SSRs and dispersed repeats. The ycf1 gene was identified as the candidate DNA barcode for the genus Justicia. Our phylogenetic results showed that Justicia is a polyphyletic group, which is consistent with previous studies. Among them, J. grossa belongs to subtribe Tetramerinae of tribe Justicieae while the other Justicia members belong to subtribe Justiciinae. Therefore, based on morphological and molecular evidence, J. grossa should be undoubtedly recognized as a new genus. Interestingly, the evolutionary history of Justicia was discovered to be congruent with the morphology evolution. CONCLUSION Our study not only elucidates basic features of Justicia whole plastomes, but also sheds light on interspecific relationships of Asian Justicia plants for the first time.
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Affiliation(s)
- Zhengyang Niu
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zheli Lin
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- School of Biology and Agriculture, Shaoguan University, Shaoguan, Guangdong, 512005, China
| | - Yi Tong
- School of Chinese Materia Medica Medical, Guangzhou University of Chinese Medicine, Guangzhou, 510006, China
| | - Xin Chen
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Life Sciences, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China
| | - Yunfei Deng
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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Garrett N, Viruel J, Klimpert N, Soto Gomez M, Lam VKY, Merckx VSFT, Graham SW. Plastid phylogenomics and molecular evolution of Thismiaceae (Dioscoreales). AMERICAN JOURNAL OF BOTANY 2023; 110:e16141. [PMID: 36779918 DOI: 10.1002/ajb2.16141] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/24/2023] [Accepted: 01/25/2023] [Indexed: 05/11/2023]
Abstract
PREMISE Species in Thismiaceae can no longer photosynthesize and instead obtain carbon from soil fungi. Here we infer Thismiaceae phylogeny using plastid genome data and characterize the molecular evolution of this genome. METHODS We assembled five Thismiaceae plastid genomes from genome skimming data, adding to previously published data for phylogenomic inference. We investigated plastid-genome structural changes, considering locally colinear blocks (LCBs). We also characterized possible shifts in selection pressure in retained genes by considering changes in the ratio of nonsynonymous to synonymous changes (ω). RESULTS Thismiaceae experienced two major pulses of gene loss around the early diversification of the family, with subsequent scattered gene losses across descendent lineages. In addition to massive size reduction, Thismiaceae plastid genomes experienced occasional inversions, and there were likely two independent losses of the plastid inverted repeat (IR) region. Retained plastid genes remain under generally strong purifying selection (ω << 1), with significant and sporadic weakening or strengthening in several instances. The bifunctional trnE-UUC gene of Thismia huangii may retain a secondary role in heme biosynthesis, despite a probable loss of functionality in protein translation. Several cis-spliced group IIA introns have been retained, despite the loss of the plastid intron maturase, matK. CONCLUSIONS We infer that most gene losses in Thismiaceae occurred early and rapidly, following the initial loss of photosynthesis in its stem lineage. As a species-rich, fully mycoheterotrophic lineage, Thismiaceae provide a model system for uncovering the unique and divergent ways in which plastid genomes evolve in heterotrophic plants.
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Affiliation(s)
- Natalie Garrett
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Juan Viruel
- Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, UK
| | - Nathaniel Klimpert
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | | | - Vivienne K Y Lam
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Vincent S F T Merckx
- Naturalis Biodiversity Center, Darwinweg 2, 2333 CR, Leiden, The Netherlands
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Sciencepark 904, 1098, XH, Amsterdam, The Netherlands
| | - Sean W Graham
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
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