湖北3种药用淫羊藿植物等位酶多样性与居群遗传结构

采用超薄平板微型聚丙烯酰胺等电聚焦电泳方法对湖北3种淫羊藿属（Epimedium L．）药用植物：柔毛淫羊藿（E．pubescens Maxim．）、箭叶淫羊藿（Esagittatum（Sieb．＆Zucc．）Maxim．）和巫山淫羊藿（Ewushanense T.S．Ying）的11个自然居群进行了等位酶种内遗传多样性和居群遗传结构以及种间遗传关系的研究。6个酶系统在3种淫羊藿植物中检测到13个酶位点共45个等位基因，分析结果表明：1）3种淫羊藿均具有较高的遗传多样性水平（A=2．6-3．2，P=69．2％-84．6％，Ho=0．274-0．377，HE=0．282-0．369），远高于多年生草本植物和依靠动物传粉植物的平均水平；2）所有居群都显著偏离Hardy—Weinberg平衡，大多数多态位点固定指数（F）明显偏离于0且正负值各半，暗示该属植物可能具有复杂的繁育系统；3）种内和种间的遗传分化度均较低，分别为GST=0．0246-0．0409和0．0495-0．1213，表明种内居群间存在较高的基因流和种间较近的遗传关系；4）聚类分析表明柔毛淫羊藿与箭叶淫羊藿的亲缘关系更近，这与形态学特征、花瓣演化趋势及系统发育分析等方面的研究的结果相吻合。讨论分析认为3种淫羊藿植物的遗传变异特性是由淫羊藿属植物异交与克隆繁殖的混合繁育系统、多年生的生活特性、古老的进化历史和种子的蚁播特性等多因素共同决定的。

Allozyme Diversity and Population Genetic Structure of Three Medicinal Epimedium Species from Hubei

Three Epimedium species, E. pubescens Maxim., E. sagittatum (Sieb. & Zucc.) Maxim., and E. wushanense T. S. Ying, which are sympatrically distributed in the western Hubei Province, have been used in traditional Chinese medicine (TCM) for about 2,000 years. Genetic variability and population genetic structure of 11 natural populations of these Epimedium species were investigated using isoelectric focusing in thin-layer polyacrylamide slab gels. Of the 22 enzyme systems prescreened, six coding for 13 loci and 45 alleles were resolved, which were used for analyzing genetic diversity and population structure at both intraspecific and interspecific levels. The results showed that: 1) high levels of genetic diversity were observed in all three species (A = 2.6-3.2, P = 69.2%-84.6%, H(O) = 0.274-0.377, H(E) = 0.282-0.369), which were higher than that of other herbaceous and animal-pollinated species with similar life-history characteristics; 2) there was significant deviation from Hardy-Weinberg Equilibrium, with one half of the loci showing heterozygote excess and the other homozygote excess, in all populations, suggesting the complicated breeding system of Epimedium species; 3) the low level of intraspecific and interspecific genetic differentiation (G(ST) = 0.0246-0.0409 and 0.0495-0.1213, respectively) indicated a high level of gene flow among populations and close genetic relationship among the three species; and 4) UPGMA cluster analysis further showed that E. pubescens was more closely related to E. sagittatum than to E. wushanense, which was in good agreement with the morphological characters and the recent phylogenetic analysis of these species. On the basis of these results, it was concluded that the mixed breeding system, long-lived perennial life form, ancient evolutionary history, and seed dispersal by ants in Epimedium are responsible for the genetic variation and population structure of these species.