中文摘要：

用6对SSR特异性引物对甘肃中部46个梨品种或类型的遗传变异和亲缘关系进行了分析，结果表明，SSR位点的期望杂合度为0．446—0．738，平均为0．639，显示了良好的品种鉴定能力。采用UPGMA聚类分析法构建的系统树将供试梨品种或类型分为7个大组：木梨组、白梨组、秋子梨组、褐梨组、西洋梨组和2个可能以秋子梨为基本种而形成的复杂的种间杂种组。唯一的砂梨品种黄花梨包含在白梨组中。新疆梨的5个品种没有独立成组，而是分别包含在木梨、白梨及秋子梨组中。一些原来根据形态学无法归类的品种和类型分别和木梨、白梨和西洋梨聚合在一起．显示出和这些梨系统的亲缘关系；木梨虽然采集地相对集中，但也显示出丰富的遗传多样性。

英文摘要：

Genetic variation and genetic relationship of 46 accessions of pear germplasm native to the middle area of Gansu province in China were analyzed using simple sequence repeat （SSR） marker with 6 pairs of SSR primers. The range of heterozygosity of SSR loci was between 0.446 and 0.738 with an average of 0.639 ,which showed the good identification power. Based on the UPGMA cluster analysis, 46 pear accessions could be obviously divided into 7 major groups, which were generally consistent with morphological classification： P. xerophila Yu, P. pyrifolia Nakai var. sinensis Y. Teng et K. Tanabe （Chinese white pears）, R ussuriensis Maxim, P. phaeocarpa Rehd. and P. communis L., and the other two groups were composed of unknown types showing some more affinities to P. ussuriensis. Huanghuali belonging to P. pyrifolia was grouped with Chinese white pears. Five accessions of P. sinkiangensis Yu were not clustered together into the same group, but scattered to groups of P. xerophila, Chinese white pear and P. uss uriensis, respectively. Some accessions that couldn＇t be classified according to morphology were clustered with P. xerophila, Chinese white pear or P. communis, which displayed genetic relationship among those pear accessions. Though P. xerophila accessions were sampled in the narrow region, they also showed the abundant genetic diversity.