Phylogenetic position and plastid genome structure of Vietorchis , a mycoheterotrophic genus of Orchidaceae (subtribe Orchidinae) endemic to Vietnam.

Autor:	Samigullin TH; A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia., Logacheva MD; 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., Averyanov LV; Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia., Zeng SJ; 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., Fu LF; 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., Nuraliev MS; 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.
Jazyk:	angličtina
Zdroj:	Frontiers in plant science [Front Plant Sci] 2024 May 24; Vol. 15, pp. 1393225. Date of Electronic Publication: 2024 May 24 (Print Publication: 2024).
DOI:	10.3389/fpls.2024.1393225
Abstrakt:	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. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2024 Samigullin, Logacheva, Averyanov, Zeng, Fu and Nuraliev.)
Databáze:	MEDLINE
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