豇豆链格孢叶斑病病原菌鉴定

Identification of Leaf Spot Pathogen Alternaria alternata in Cowpea

2015年初,在海南省乐东县豇豆主产区发现一种豇豆新病害——豇豆叶斑病,主要危害豇豆叶片。为了明确病害病原菌,为农户今后开展田间防治提供科学有效的依据,笔者拟通过观察豇豆田间发病特征,并对病菌进行分离纯化、致病性测定,结合形态学观察及分子生物学鉴定确定病原菌。结果表明:豇豆叶斑病发病初期,在叶片中央产生豌豆大小的灰色或者浅褐色病斑,病斑中央呈灰白色,叶片边缘伴有一定面积的枯萎,后期病斑连接成片,造成叶片枯萎坏死,将其rDNA-ITS和rDNA-28S序列进行BLAST比对,结合形态学观察,初步鉴定该病害致病菌为链格孢(Alternaria.sp.)。

A new disease named leaf spot disease of cowpea was observed in Ledong county,Hainan province in 2015,and it infected mainly cowpea leaves.In order to identify the pathogen of the leaf spot disease and provide reference for the control and prevention of the leaf spot disease,the characteristics of the disease were observed in the field,and pathogens of the leaf spot disease were isolated from the infected leaf samples and purified for pathogenic identification.The pathogens were identified through morphological observation of the disease and the molecular biological identification of the isolates.Morphological observation showed that there were gray or light brown spots or lesions in the center part of the leaf,which had a similar size with pea in the early stages,were grayish white in the central part with a certain area of wilting in the leaf margin,and at the late stage coalesced into large patches,resulting to wilting and killing of the infected leaves.Molecular biological identification showed that the pathogen shared a 99%homogeneity of sequences of and 28 S rDNA and ITS rDNA of the pathogen with the related sequences in the GenBank by using BLAST.Both the field morphological observation and the molecular biological identification showed that the pathogen causing the leaf spot disease of cowpea was Alternaria.alternata.