沙生植物-大赖草克隆多样性

A Study on the Clonal Diversity of Psammophyte-Leymus racemosus

为了解大赖草在沙漠中种群结构维持稳定的机制,以便更有效地保护和利用其野生植物资源,本试验利用ISSR标记技术对两个典型生境(沙地及沙丘)的大赖草种群的克隆多样性及克隆结构进行了初步研究。NTSYS分析表明:(1)两个种群(共170个样本)均为多克隆种群,共包含98个基因型,且均为局限基因型,群体间的克隆分化较大;(2)大赖草的克隆多样性较高,Simpson指数(D)平均为0.882,基因型比率(PD)平均为0.562,其中克隆多样性表现为HBX>HBN,大赖草能够以根状茎进行克隆繁殖,而保持较高的克隆多样性,这主要与该物种兼性克隆繁殖及多克隆起源有关;(3)两个居群的克隆结构也有明显差异,HBX种群(生长在沙本文地)的克隆生长空间格局表现为游击型,而HBN种群(生长在沙丘)的克隆结构则表现为密集型,这可能是由于大赖草适应异质性生境;(4)进一步对影响大赖草克隆多样性的因素进行了分析,并提出了保护策略。

In order to understand the mechanisms of Leymus racemosus to maintain a stable population structure in the desert so that its wild plant resources could be more effectively protected and utilized. The study preliminarily analyzed the population diversity and clonal structure of L. racemosus in two typical habitats（sands and dunes） by using ISSR markers. The analysis of NTSYS showed that： Firstly, both of the two populations（170samples） were polyclonal populations, which contained 98 confined genotypes, and genotype clone differentiation among populations was large; Secondly, L. racemosus has a high clonal diversity, the average Simpson index（D）was 0.882, average genotype ration（PD） was 0.562, the clonal diversity was HBX〉HBN. The main reason why L.racemosus could use rhizome reproductive for cloning, and maintaining a high clonal diversity is the facultative clonal propagation and the polyclonal origin of the species; Thirdly, the clone structures of two populations were significantly different. HBX population（grown in sands） had a spatial pattern of guerilla performance in clonal growth, while HBN population（grow in dunes） had an intensive cloning structure. It may be due to the adaptation of L. racemosus to environmental heterogeneity; Finally, the factors affecting the clonal diversity of L. racemosus was further studied and the conservation strategy was suggested.