云南核桃叶枯病病原鉴定及其生物学特性

Identification and biological characteristics of a new pathogen causing the walnut leaf blight in Yunnan province

为明确引起云南核桃叶枯病的病原及其生物学特性,本文对分离自叶枯病病斑上的一株拟盘多毛孢进行了形态学和分子生物学鉴定,并通过柯赫氏法则验证其致病性;采用生长速率法、悬滴法和载玻片法研究其菌丝生长和孢子萌发的生物学特性。结果表明,该菌株为小孢拟盘多毛孢Pestalotiopsis microspora,是引起云南核桃叶枯病的新病原。该病原菌的最适生长温度为20~25℃,最适光周期L//D=12 h//12 h,最适生长pH为4~8。病原菌的分生孢子萌发受pH和湿度的影响较大,在中性及碱性环境下不萌发,最适萌发pH为4~5;在高于90%的相对湿度下才能萌发。分生孢子在20~25℃下萌发率最高,全光照最适于孢子萌发;核桃叶汁液对分生孢子萌发有显著的促进作用。

In the present study, the identification and biological characteristics of the pathogen causing the walnut leaf blight in Yunnan province were studied. The pathogenicity test was done based on the Koch’s postulates;the pathogen was identified based on morphological characteristics and molecular evidence, and the biological characteristics were determined by using the methods including colony growth and spore germination. The results showed that the strain was identified as Pestalotiopsis microspora as the new pathogen of walnut leaf blight. The growth of P.microspora was best at 20-25℃, pH 4-8 on PDA medium, and the optimal light conditions were alternation of 12 h light and 12 h dark. The conidia were harder to germinate below 90% relative humidity or above pH 6. The conidia were best to germinate at 20-25℃;the optimum light conditions were full light, and the optimum pH values were 4-5. The walnut leaf juice had a remarkable promotion function to mycelium growth.