基于核基因LEAFY的中国珍稀濒危植物中华水韭的遗传多样性分析

利用核基因LEAFY第二个内含子片段对中国现存中华水韭（Isoetes sinensis Palmer）的遗传多样性进行分析，探讨了中华水韭自然居群的遗传多样性结构及其形成机制。结果显示：现存中华水韭7个自然居群共105个样本中存在78个单倍型，单倍型多样性（H_d）为0.989，核苷酸多样性（π）为0.021，遗传差异主要存在于居群内（72%），且存在较高的基因流（N_m=0.59）。同时，居群遗传学分析结果发现中华水韭居群不存在明显的谱系地理格局（G_ST>N_ST）；Mantel检验中Rxy值为-0.286，P（rxy-rand≥rxy-data）值为0.370，表明居群遗传距离和地理距离之间没有明显相关性；UPGMA聚类分析显示处于海拔较高位置的2个居群与其它5个居群遗传关系较远；中性检验（Taijima's D、Fu & Li's D^*和F^*）检测结果均为负值，基于稳定模型的失配分布检测显示为多峰。根据中华水韭居群的地理位置，推测中华水韭的遗传结构可能与水系、海拔分布及其杂交后代多倍化的物种形成过程相关。

Analysis on the genetic diversity of endangered Isoetes sinensis Palmer from China based on the second intron of LEAFY

We used the second intron of the LEAFY gene to analyze the genetic diversity of Isoetes sinensis Palmer from China. In total, 105 samples were collected from seven populations. From these I. sinensis samples, 78 haplotypes were discovered, with a haplotype diversity of 0.989 and nucleotide diversity of 0.021. Results showed that genetic differentiation coefficient G_ST=0.283, N_ST=0.298, G_ST>N_ST, N_m=0.59; Mantel test, Rxy=-0.286, P (rxy-rand≥rxy-data)=0.370, and 72% of the total variation existed within populations. UPGMA cluster showed that the two high altitude populations had distant genetic relationships with the other five populations. The neutrality test, Tajima's D, Fu & Li's D^* and F^* tests were negative, and the mismatch distribution test based on a stable model was multimodal. According to the geographic location of I. sinensis, its genetic structure was related to the drainage, altitude, and process of hybrid polyploidization.