中国3种松干锈菌在随机扩增DNA多态性水平上的遗传分化

用ＲＡＰＤ手段分析了我国３种松干锈菌Ｃｒｏｎａｒｔｉｕｍｒｉｂｉｃｏｌａ、Ｃ．ｆｌａｃｃｉｄｕｍ及Ｃ．ｑｕｅｒｃｕｕｍ在ＤＮＡ水平上的遗传分化。用５个随机引物从１０个菌株（含１个不同属参照菌株）中检测出５１个多态ＤＮＡ片段进行聚类分析，３种锈菌清晰地显示为不同类群，此结果为传统分类的成立提供了分子遗传学证据。３种锈菌中Ｃ．ｒｉｂｉｃｏｌａ和Ｃ．ｆｌａｃｉｄｕｍ的亲缘关系较近，这同由症状和冬孢子寄主反映出的相似关系一致。种内菌株间存在遗传差异，但其程度小于种间差异。锈孢子及冬孢子寄主都不同的Ｃ．ｆｌａｃｉｄｕｍ菌株间差异明显，可能反映着专化型分化的遗传学基础。不同松树寄主的Ｃ．ｑｕｅｒｃｕｕｍ菌株间也存在差异，暗示我国的Ｃ．ｑｕｅｒｃｕｕｍ同北美一样存在对松类的寄生专化性分化。研究结果还提示松干锈菌的遗传分化主要同寄主有关，而与地理分布关系不大。

GENETIC DIFFERENTIATION AMONG THREE PINE-STEM RUST FUNGI FROM CHINA AS ESTIMATED BY RANDOM AMPLIFIED POLYMORPHIC DNA

Genetic differentiation among three pine stem rust fungi from China,i.e., Cronartium ribicola, C.flaccidum and C.quercuum, was assessed by random amplified polymorphic DNA(RAPD). Ten isolates(including an outgroup isolate)with different host and/or geographical origins were subjected to study. Pairwise similarity analysis was conducted on 51 RAPD loci detected by five selected primers. The result shown that although there were intraspecific variations, three rust pathogens were clearly separated as distinctive groups, thus justifying these traditional fungal taxa by using DNA data. Genetic relatedness between C.ribicola and C.flaccidum was closer than that between C.quercuum and either of the former two,this being consistent with the relationship reflected by disease symptom and telial stage host range of these pathogens.High degree of intraspecific divergence was found between two C.flaccidum isolates which differ from each other in host specialization over their life circles, possibly demonstrating the genetic background underlying these two supposed formae speciales. Intraspecific variation was also found among C.quercuum isolates with different pine hosts, suggesting that the host specialization of C.quercuum in aceial stage as reported in Northern America may also exist in China. Evidences were also obtained that host adaptation,rather than geographic factors, is the primary force to drive genetic differentiation of the pine stem rust fungi.