苦玄参褐斑病病原鉴定及致病因素分析

Pathogen Identification of Picria felterrae Brown Spot and Analysis on the Pathogenic Factor

为明确近年来引起广西梧州地区苦玄参(Picria felterrae Lour.)褐斑病的病原菌种类及致病因素,依据柯赫氏法则进行了致病性测定和病原菌验证,通过形态学观察、rDNA-ITS序列分析确定病原菌;通过对不同光照条件下病情调查,分析光照对该病害发生的影响。结果表明,病原菌形态特征与[Alternaria porri(ELL.)Ciferri]一致,其rDNA-ITS序列与GenBank中[Alternaria porri(ELL.)Ciferri]相似性达99%;强光利于病原菌菌丝生长、孢子产生及萌发。可见梧州地区苦玄参褐斑病病原菌为葱链格菌[Alternaria porri(ELL.)Ciferri];光照是诱发苦玄参褐斑病的主要致病因素。

The study aimed to identify the organism that leads to the Picria felterrae brown spot in Wuzhou and to analyze the pathogenic factor. The fungus was isolated from infected plants according to Koch ’s rule. The identification of the pathogen was carried out mainly based on the morphological characters and molecular analysis of internal transcribed spacer(ITS) sequences; the investigation of disease was done under different illumination intensity. The morphological characters of the pathogenic isolate were in agreement with Alternaria porri(ELL.) Ciferri. When compared with sequences in GenBank,the ITS sequence of the pathogen was 99% similar to that of A. porri; the disease was serious in the light; the illumination was beneficial for mucelium growth, spore production and germination. The pathogen causing P. felterrae brown spot in Wuzhou was identified as A. porri; illumination was the main pathogenic factor of the disease.