进境美国大豆中值得关注的真菌 Diaporthe novem

A noteworthy fungus Diaporthe novem on soybean imported from America

采用常规平板分离法,从一批进境的美国大豆样品中获得1株可疑的间座壳属菌株MDD57。经形态学观察发现,该菌株在PDA培养基上产生分生孢子器,且同时产生大量α型和β型分生孢子,未见有性阶段。经ITS和tef1α基因扩增、核酸序列比对分析,发现该菌株同GenBank中2株Diaporthe novem菌株的基因序列同源性达100%,且聚类于同一发育分支。经柯赫氏法则验证,该菌株可侵染大豆茎部和叶片,引起典型的间座壳属病害症状。根据以上结果,确定进境美国大豆中携带有D.novem,这是天津口岸首次从美国大豆中截获该危险性病菌。该病菌同大豆北方茎溃疡病菌、大豆南方茎溃疡病菌、大豆拟茎点种腐病菌同为近似种,引起大豆茎秆溃疡及种子腐烂,危害严重。

A fungal strain MDD57 was isolated from soybean seeds imported from America by conventional isolation and culture method.Morphological observation showed that the strain produced pycnidia and a lot ofα-conidia andβ-conidia on PDA medium,but there was no teleomorph stage.ITS and tef1αgene amplification and DNA sequence alignment indicated that the sequences of the strain were the most similar to the two sequences of Diaporthe novem deposited in GenBank with 100%identity,and the strain was clustered with the strain of D.novem.Koch’s rule verification proved that the strain infected soybean stems and leaves,forming typical Diaporthe symptoms.The isolate was identified as D.novem.This is the first interception report of D.novem from American soybean at Tianjin port.The pathogen is similar to D.caulivora,D.aspalathi and D.longicolla,causing stem canker and seed rot of soybean and bring about serious damage.