草莓丝核菌根腐病的病原菌鉴定

 由丝核菌引起的根腐病是草莓生产上的重要病害之一。本研究基于形态学、菌丝细胞核荧光染色、菌丝融合群测定、rDNA-ITS序列分析和柯赫氏法则验证,对北京地区引起草莓根腐病的丝核菌进行了鉴定。2014年从北京市昌平区温室草莓根腐病病样中分离纯化获得的3个代表菌株,经形态学和细胞核荧光染色,确定均为双核丝核菌(binucleate Rhizoctonia, BNR),且与双核丝核菌AG-A融合群菌株发生菌丝融合,菌株CP-Z的rDNA-ITS序列与GenBank中丝核菌属的有性型角担菌属(Ceratobasidium)AG-A融合群 4个菌株的相似性达100%。菌株CP-Z接种草莓根部,引起根系变黑、腐烂,植株死亡,从接种发病的根部可重新分离到双核丝核菌。双核丝核菌AG-A融合群引起草莓根腐病为国内首次报道。该病原菌菌丝生长适温为25℃~28℃。

Identification of pathogen causing strawberry Rhizoctonia root rot

Root rot caused by Rhizoctonia is one of the most important diseases in strawberry. In this study, the pathogen of strawberry root rot was identified based on morphology, nucleus fluorescence staining, hyphal anastomosis test, rDNA-ITS sequence analysis and Koch′s postulates. The isolates were obtained from the diseased roots of strawberry collected from greenhouse in Changping district, Beijing in 2014. Three isolates were identified as binucleate Rhizoctonia (BNR) based on their morphological characteristics and nuclei staining. Hyphae of the isolates fused with an AG-A tester isolate. rDNA-ITS sequence (GenBank Accession No. KP893156) of isolate CP-Z exhibited 100% similarity with four Ceratobasidium sp. AG-A isolates. Strawberry seedlings inoculated with isolate CP-Z showed black root rot and died gradually. Binucleate Rhizoctonia was re-isolated from the ino-culated strawberry roots. This is the first report of BNR AG-A causing root rot of strawberry in China. The optimum temperature for mycelial growth of the pathogen is 25℃~28℃.