无柄醉鱼草与大叶醉鱼草的遗传多样性解析

Analysis of Genetic Diversity of Buddleja sessilifolia and B. davidii

关键词:  遗传多样性  遗传结构  极小种群野生植物  濒危物种  无柄醉鱼草  大叶醉鱼草  保护建议

Key words:  genetic diversity  genetic structure  Plant Species with Extremely Small Populations (PSESP)  endangered species  Buddleja sessilifolia  Buddleja davidii  conservation recommendations

摘要:

无柄醉鱼草(Buddleja sessilifolia)是狭域分布的极小种群野生植物(Plant Species with Extremely Small Populations, PSESP),大叶醉鱼草(B.davidii)则是广布种,二者亲缘关系较近,且同为四倍体。通过比较濒危物种与近缘广布种的遗传多样性,可以了解濒危物种的演化历史,为制定保护策略提供理论依据。本研究通过简单重复序列(Simple Sequence Repeats, SSR)分子标记对无柄醉鱼草5个居群(126个个体)和大叶醉鱼草14个居群(206个个体)进行遗传多样性和遗传结构解析,并提出对无柄醉鱼草的保护建议。结果表明,无柄醉鱼草和大叶醉鱼草各居群的期望杂合度(He)平均值分别为0.606、0.775,Shannon's多样性指数(I)平均值分别为1.162、1.729,两个物种均具有较高的遗传多样性,但广布种大叶醉鱼草遗传多样性水平高于狭域种无柄醉鱼草;无柄醉鱼草和大叶醉鱼草遗传分化系数(F_ST)分别为0.043和0.024,两个物种居群间遗传分化程度均较低。遗传结构分析结果表明,无柄醉鱼草5个居群可划分为2个集群,居群间地理距离与遗传距离不存在相关性;大叶醉鱼草14个居群可划分为3个集群,居群间地理距离与遗传距离相关。结合野外居群现状,建议对无柄醉鱼草划分保护单元,重点对丹珠居群和独龙江隧道口居群开展就地保护,同时采取种质资源收集、人工繁育等保护措施。

Abstract:

Buddleja sessilifolia is a narrowly distributed Plant Species with Extremely Small Populations (PSESP),whereas B.davidii a widely distributed species,are closely related with B.sessilifolia,and both are tetraploids. By comparing the genetic diversity of an endangered species with narrow distribution to their widely distributed relatives can lay a theoretical basis for conservation strategies.Genetic data can uncover crucial insights into the evolutionary history of the threatened species.In this study,we analyzed the genetic diversity and genetic structure of 5 populations (126 individuals) of B.sessilifolia and 14 populations (206 individuals) of B.davidii using Simple Sequence Repeats (SSR) molecular markers,and provide recommendations for the conservation management of B.sessilifolia.Our results demonstrated that:the expected heterozygosity (He) of B.sessilifolia and B.davidii average value were 0.606 and 0.775,respectively,and Shannon's diversity index (I) for B.sessilifolia and B.davidii average value were 1.162 and 1.729,respectively.The high genetic diversity seen in both B.sessilifolia and B.davidii,but the genetic diversity of the widely distributed B.davidii was higher than that of the narrowly distributed B.sessilifolia.In both B.sessilifolia and B.davidii, low levels of genetic differentiation were found between their populations,with genetic differentiation coefficients (F_ST) of 0.043 and 0.024,respectively.Genetic structure analysis revealed that the 5 populations of B.sessilifolia fell into two clusters.Moreover,there was no correlation between geographical and genetic distance among the populations.The 14 populations of B.davidii fell into three clusters,and there was a correlation between geographical distance and genetic distance among the populations.Based on the current situation of the populations in the field,we recommend that populations of B.sessilifolia should be divided into conservation units,with emphasis on the in situ conservation of the Gongshan,Danzhu and Gongshan,Dulongjiang Crossing populations.In addition,germplasm collection,artificial breeding,and other conservation efforts should be carried out to protect this endangered species.