中文摘要：

为探明茎直黄芪（Astragalus strictus）不同组织部位内生真菌种群分布及其物种多样性,对采自西藏工布江达县的茎直黄芪样品,运用形态学和rDNA-ITS序列分析技术鉴定其种属,并计算多样性指数。结果表明：从茎直黄芪424个组织块中分离到内生真菌336株,分属7纲、9目、10科、13属,其中Alternaria tenuissima分离率最高为32.14%,是优势种属,其次是Undifilum oxytropis,分离率为19.05%;多样性指数显示,茎直黄芪不同组织部位内生真菌多样性指数不同,花中内生真菌香农-维纳指数（2.16）及辛普森指数（0.154）及均匀度指数（0.80）均最高,表明其多样性最高,叶次之,茎最低。表明茎直黄芪不同组织内生真菌的数量、种属组成及多样性存在明显差异,花是内生真菌定植的主要部位,且其多样性最高。

英文摘要：

Fungal endophyte were isolated from Astragalus strictus samples collected from Gongbujiangda city of Tibet to investigate the species diversity and distribution of endophyte.The species and genus of endophyte were identified by the traditional morphology and rDNA-ITS sequence analysis,and diversity index was calculated by Biodap.The results showed that 336 fungal colonies were isolated from 424 samples,which were combined to 21 kinds of different endophytic fungus.Under all the conditions of sterilization,Alternaria tenuissima was the dominant species in these species with the relative frequency of32.14%,followed with Undifilum oxytropis（19.05%）.Diversity indexes showed that the diversity index of fungal endophyte differed from different tissues.The Shannon-Weiner index,simpson index and evenness index of fungal endophyte in flower were all highest,which was 2.16 0.154,and 0.80,respectively,followed by leaf and stem.In conclusion,there was an obvious difference in quantity,species and diversity of the endophyte among different tissues of Astragalus strictus.Flower was the most vulnerable to colonization by the endophyte,whose diversity was the maximum.