福建省辣椒疫霉菌群体结构表型特征分析

Phenotypic structure of Phytophthora capsici populations on pepper in Fujian,China

为了明确福建省辣椒疫霉菌群体遗传结构的表型特征,对分离自福建省15个市(县)的300株辣椒疫霉菌的交配型、甲霜灵敏感性及生理小种进行了测定。结果显示,288株为A2交配型,12株为A1交配型,出现频率分别为96%和4%,以A2占优势,在各采集点均有分布。263株对甲霜灵表现敏感,28株为中间型,9株为抗性,分别占总体的87.67%、9.33%和3.00%,甲霜灵敏感菌株为主要菌系。根据菌株对辣椒疫霉菌生理小种鉴别寄主的致病性测定结果,可将辣椒疫霉菌划分为3个生理小种,其中168株为小种3,126株为小种2,6株为小种1,分别占56%、42%和2%,小种3为福建辣椒疫霉菌优势小种。

To characterize the phenotypic structure of Phytophthora capsici populations on pepper in Fu-jian, 300 isolates of P. capsici collected from different regions in Fujian were assessed based on mating type, metalaxyl response and physiological race. The results showed that 288 isolates belonged to A2 mating type with frequency of 96% and 12 isolates were A1 mating type with frequency of 4%, respec-tively. A2 mating type was the majority and distributed in all sampling regions. Meanwhile, 263 iso- lates were sensitive to metalaxyl, 28 isolates were intermediate sensitivity to metalaxyl, and 9 isolates were resistant to metalaxyl, the frequency of sensitive, intermediate and resistant isolates were 87.67%, 9.33% and 3.00%, respectively. Metalaxyl-sensitive isolates was frequently in Fujian. In addition, based on the pathogenicity on a set of four pepper differential lines, tested isolates were classified into three physiological races, and 168 isolates were physiological race 3 with the frequency of 56%, 126 iso- lates were physiological race 2 with the frequency of 42%, and the remaining 6 isolates were physiologi- cal race 1 with the frequency of 2%. These data demonstrated that physiological race 3 was dominant in Fujian.