芝麻棒孢叶斑病病原菌鉴定与致病力比较

Identification and pathogenicity comparison of Corynespora cassiicola causing leaf spot on sesame

为明确芝麻叶斑病病原菌及其致病力,本研究以河南不同地区芝麻上分离所得叶斑病分离物为研究对象,通过形态观察和分子鉴定探讨这些分离物的分类属性,并且进行离体叶片和活体茎杆接菌,进一步探究了不同菌株的致病力差异。结果显示分离所得的6株芝麻叶斑病分离物的菌落形态、生长速率和产孢量存在差异,分生孢子多数呈倒棍棒状,具隔膜,6个菌株的ITS序列与GenBank中Corynespora cassiicola的一致性达99%以上,结合形态特征与ITS序列将其鉴定为山扁豆生棒孢。室内人工接菌芝麻发现,这6个菌株的致病力存在显著的差异;在芝麻叶片上,20180909-03属强致病力菌株,20180821-01、20180909-05和20180824-01属中等致病力菌株,20180904-02-02和SF1-1属弱致病力菌株;在芝麻茎杆上,20180824-01致病力最强,其次是20180821-01、20180909-03和20180909-05,SF1-1和20180904-02-02致病力最弱。研究结果证明山扁豆生棒孢不同菌株在芝麻上的致病力存在明显的分化。

In order to clarify the pathogen and its pathogenicity of sesame leaf spot,the isolates from sesame diseased leaves in different areas of Henan Province were identified based on morphology and molecular biology.Moreover,the pathogenicity of different isolates was further tested by in vitro and in vivo inoculation.The results showed that there were differences in colony morphology,growth rate and sporulation of six isolates associated with sesame leaf spot.Most of the conidia were rod-shaped,having many septa.The ITS sequences of six isolates were more than 99%consistent with those of Corynespora cassiicola in GenBank.The isolates were identified as C.cas-siicola based on morphological characteristics and ITS sequences.The results of indoor artificial inoculation of sesame showed that,the pathogenicity of six strains was significantly different.As for the sesame leaves,20180909-03 was a strong pathogenic strain,20180821-01,20180909-05 and 20180824-01 were moderately pathogenic strains,20180904-02-02 and SF1-1 were weak pathogenic strains.In the sesame stems,20180824-01 was highly pathogenic strain,followed by 20180821-01,20180909-03,20180909-05,SF1-1 and 20180904-02-02 being less pathogenic strains.It was proved that a distinct phenomenon of pathogenicity differentiation exists among C.cassiicola isolates from sesame.