Samigullin Tahir H, Logacheva Maria D, Averyanov Leonid V, Zeng Si-Jin, Fu Long-Fei, Nuraliev Maxim S
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.
Front Plant Sci. 2024 May 24;15:1393225. doi: 10.3389/fpls.2024.1393225. eCollection 2024.
The orchid genus 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, , occurs in a single location in northern Vietnam within a lowland limestone karstic area. and , in contrast, are confined to mountains of southern Vietnam, far away from any limestone formations. Taxonomic placement of 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 ( and ) 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 into the subtribe Orchidinae (tribe Orchideae, subfamily Orchidoideae). This leads to a conclusion that the previously highlighted similarities in the rhizome morphology between and certain mycoheterotrophic genera of the subfamilies Epidendroideae and Vanilloideae are examples of a convergence. is deeply nested within Orchidinae, and therefore the subtribe Vietorchidinae is to be treated as a synonym of Orchidinae. In the obtained phylogenetic reconstructions, is sister to the photosynthetic genus . is restricted to limestone mountains, which allows to speculate that association with limestone karst is plesiomorphic for . Flower morphology is concordant with the molecular data in placing into Orchidinae and strongly supports the assignment of the genus to one of the two major clades within this subtribe. Within this clade, however, shows no close structural similarity with any of its genera; in particular, the proximity between and has never been proposed. Finally, we assembled the plastid genome of , which is 65969 bp long and contains 45 unique genes, being one of the most reduced plastomes in the subfamily Orchidoideae. The plastome of 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.
该兰花属包含三个物种，均于21世纪被发现。这些物种均无叶绿素，为菌根异养型，且均为越南特有种。该属的模式种在越南北部低地石灰岩岩溶地区的一个地点被发现。相比之下，另外两个物种局限于越南南部的山区，远离任何石灰岩地层。由于形态学亲缘关系不明确，该模式种的分类位置一直不确定。同时，该属从未被纳入分子系统发育研究。我们基于三个DNA数据集研究了该属两个物种（[物种名1]和[物种名2]）的系统发育关系：（1）一个包含两个核区域的数据集；（2）一个包含两个质体区域的数据集；（3）一个采用整个质体基因组数据的数据集。我们的系统发育重建支持将[物种名1]归入亚族红门兰亚族（红门兰族，兰亚科）。由此得出结论，先前强调的[物种名1]与树兰亚科和香荚兰亚科某些菌根异养属在根状茎形态上的相似性是趋同的例子。[物种名1]在红门兰亚族中处于深度嵌套位置，因此越南兰亚族应被视为红门兰亚族的同义词。在得到的系统发育重建中，[物种名1]是光合属[另一属名]的姊妹种。[物种名1]局限于石灰岩山区，这使得推测与石灰岩岩溶的关联对[物种名1]来说是原始性状。花的形态与将[物种名1]归入红门兰亚族的分子数据一致，并有力地支持将该属归入该亚族内两个主要分支之一。然而，在这个分支内，[物种名1]与其任何属都没有紧密的结构相似性；特别是，从未有人提出[物种名1]与[另一属名]之间的亲缘关系。最后，我们组装了[物种名1]的质体基因组，其长度为65969 bp，包含45个独特基因，是兰亚科中质体基因组最简化的之一。与最接近的已研究自养物种相比，[物种名1]的质体基因组没有任何重排，并且具有大幅收缩的反向重复序列。未检测到对质体蛋白质编码序列有正向选择作用的迹象。
