Wang Xin-Hui, Wu Wei, Jian Shu-Guang
Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 People's Republic of China.
University of Chinese Academy of Sciences Beijing 100040 People's Republic of China.
Appl Plant Sci. 2019 Oct 16;7(10):e11292. doi: 10.1002/aps3.11292. eCollection 2019 Oct.
is an important gymnosperm genus, and the most diverse of all cycad genera. The complex of species are morphologically similar and difficult to distinguish due to a lack of genomic resources.
We characterized the transcriptomes of two closely related and endangered species endemic to Hainan, China: and . Three single-copy nuclear genes in the complex were sequenced based on these transcriptomes, enabling us to evaluate the species boundaries using the multispecies coalescent method implemented in the Bayesian Phylogenetics and Phylogeography program.
We obtained 68,184 and 81,561 unigenes for and s, respectively. We identified six positively selected genes that are mainly involved in stimulus responses, suggesting that environmental adaptation may have played an important role in the relatively recent divergence of these species. The similar distribution peaks at 1.0 observed for the paralogs in the two species indicate a common whole-genome duplication event. Our species delimitation analysis indicated that the complex consists of three distinct species, which correspond to the previously reported morphological differences.
Our study provides valuable genetic resources for species and guidance for the taxonomic treatment of the complex, as well as new insights into evolution of species within .
苏铁属是一个重要的裸子植物属，也是所有苏铁属中物种最为多样的。该属物种复合体在形态上相似，由于缺乏基因组资源而难以区分。
我们对中国海南特有的两个亲缘关系密切且濒危的苏铁物种的转录组进行了特征分析，分别是[物种一]和[物种二]。基于这些转录组对苏铁属复合体中的三个单拷贝核基因进行了测序，使我们能够使用贝叶斯系统发育和系统地理学程序中实现的多物种溯祖方法来评估物种界限。
我们分别为[物种一]和[物种二]获得了68,184个和81,561个单基因。我们鉴定出六个主要参与刺激反应的正选择基因，这表明环境适应可能在这些物种相对较近的分化中发挥了重要作用。在两个物种中观察到的旁系同源基因相似的[某种分布]峰值在1.0处，表明存在一个共同的全基因组复制事件。我们的物种界定分析表明，苏铁属复合体由三个不同的物种组成，这与先前报道的形态差异相对应。
我们的研究为苏铁属物种提供了有价值的遗传资源，为苏铁属复合体的分类处理提供了指导，同时也为苏铁属内物种的进化提供了新的见解。
