【摘要】 分离纯化了云南楚雄、宁夏银川、北京通县、上海七宝镇、四川西昌５个地区的灰飞虱体内类酵母型共生菌（Ｙｅａｓｔ－ｌｉｋｅ Ｓｙｍｂｉｏｎｔｓ， ＹＬＳ），并对其１８Ｓ ｒＤＮＡ的约６００ｂｐ的序列进行了测定。结合已有的序列，构建了不同宿主的ＹＬＳ的分子系统树。结果表明，灰飞虱的ＹＬＳ属于子囊菌亚门Ｐｙｒｅｎｏｍｙｃｅｔｅｓ纲，与此纲的Ｈ ｃｈｒｙｓｏｏｐｅｒｍｕｓ亲缘关系最近。我国各地区及日本的灰飞虱体内ＹＬＳ可能是同一种的不同地理群体，不同的ＹＬＳ在其宿主分化后才选择了不同的宿主，之后与其宿主长期共同进化、共同适应。更多还原

【Abstract】 The yeast-like symbionts are isolated and purified from the small brown planthoppers collected from five areas in China. The 18S rDNA sequences of them are determined. Combined with the sequences of other fungi, we have constructed a comprehensive phylogenetic bee. The results suggested that the taxonomic positions of the YLS are in the class Pyrenomycetes in the subphylum Ascomycotina and the YLS have the closest relationship with H chrysospermus. The YLS of different areas in China and Japan may belong to different geographical populations of one species. We could also draw a conclusion that there are independent acquisitions of various symbionts in differentiated hosts更多还原