College of Life Science and Technology, Xinjiang University, Urumqi 830046, China.
Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China.
Genes (Basel). 2022 Jul 29;13(8):1361. doi: 10.3390/genes13081361.
is an endangered species, narrowly endemic to Hainan and Southwest Guangdong. The taxonomic classification of remains controversial. Moreover, studying endangered species is helpful for current management and conservation. In this study, the first complete chloroplast genome of was assembled and compared with other species. The chloroplast genome size of was 154,552 bp, consisting of 87 protein-coding genes, 38 tRNA genes, 8 rRNA genes, and one pseudogene. The ψ gene was lost in the cp genome of , but it was detected in four other species of The inverted repeats (IR) regions have a relatively lower length variation compared with the large single copy (LSC) and small single copy (SSC) regions. Long repeat sequences and simple sequence repeat (SSR) were detected, and most SSR were distributed in the LSC region. Codon usage bias analyses revealed that the RSCU value of the genus has almost no difference. As with most angiosperm chloroplast genomes, protein-coding regions were more conservative than the inter-gene spacer. Seven genes (, , , , , , and ) were detected under positive selection in different species, which may result from adaptive evolution to different habitats. Phylogenetic analyses show the cluster in two main groups; were closest to . A highly suitable region of was simulated by Maxent in this study; it is worth noting that the whole territory of Taiwan has changed to a low fitness area and below in the 2050 s, which may not be suitable for the introduction and cultivation of In addition, limited by the dispersal capacity of , it is necessary to carry out artificial grafts to expand the survival areas of . Our results provide valuable information on characteristics of the chloroplast genome, phylogenetic relationships, and potential distribution range of the endangered species .
海南龙血树是一种濒危物种，仅狭窄分布于海南和粤西南地区。其分类学地位仍存在争议。此外，研究濒危物种对于当前的管理和保护具有重要意义。本研究首次组装并比较了海南龙血树的完整叶绿体基因组。海南龙血树的叶绿体基因组大小为 154,552 bp，包含 87 个蛋白编码基因、38 个 tRNA 基因、8 个 rRNA 基因和 1 个假基因。ψ基因在海南龙血树的 cp 基因组中丢失，但在其他四个物种中检测到。与大、小单拷贝区相比，反向重复区（IR）具有相对较低的长度变异。检测到长重复序列和简单重复序列（SSR），大多数 SSR 分布在 LSC 区。密码子使用偏性分析表明，该属的 RSCU 值几乎没有差异。与大多数被子植物叶绿体基因组一样，蛋白编码区比基因间间隔区更保守。在不同的物种中检测到 7 个基因（,,,,,, 和 ）受到正选择，这可能是由于对不同生境的适应性进化。系统发育分析表明，海南龙血树聚为两个主要分支；与其他物种相比，海南龙血树与戟属最为接近。本研究通过 Maxent 模拟了海南龙血树的高适合度区域；值得注意的是，整个台湾地区在 2050 年代以后已转变为低适合度区甚至不适宜区，这可能不利于海南龙血树的引入和栽培。此外，受其扩散能力的限制，有必要进行人工嫁接以扩大其生存区域。本研究结果为濒危物种海南龙血树的叶绿体基因组特征、系统发育关系和潜在分布范围提供了有价值的信息。
