通过稀释分离法对海南、江苏两地玉米枯叶进行分离和纯化，根据病原菌菌落生长速度、颜色、形态等选取17个代表性菌株进行形态学、分子生物学鉴定。选取其中3个代表性菌株C1、C2、C12的孢子悬浮液喷雾接种玉米叶片，观察发病情况，根据柯赫氏法则，对枯叶进行再分离，观察再分离菌株与接种菌株的不同。结果表明，引起玉米叶枯病病原为枝孢属真菌(Cladosporium)，在形态学鉴定的基础上，将多基因序列在NCBI数据库中比对及系统发育树分析，确认17个供试菌株分为3类，包括极细枝孢(C. tenuissimum)、枝状枝孢(C. cladosporioides)、耐盐枝孢(C. halotolerans)。3个代表性菌株C1、C2、C12有伤、无伤接种7 d后，均引起玉米叶枯，有伤接种发病速度较快，病斑扩展也较快，从病斑处再分离，均可分离出接种菌株。引起海南玉米叶枯病的病原菌为C. tenuissimum、C. cladosporioides、C. halotolerans，其中，C. tenuissimum为优势种；引起江苏玉米叶枯病的病原菌为C. cladosporioides。

Identifying the pathogenic species is crucial for effective control of maize leaf blight. Dilution & separation method was employed in the study of maize blighted leaves from Hainan and Jiangsu individually. Seventeen representative strains were chosen based on characteristics such as colony growth rate, color, and morphology for morphological and molecular biological identification. Suspensions of spores from the three representative strains C1, C2 and C12 were sprayed onto maize leaves to observe disease development. To compare the isolated strains with the inoculated ones were reisolated from blighted leaves based on Koch’s postulates. The results showed that the pathogens which caused maize leaf blight were belonged to Cladosporium genus. Based on morphological identification, NCBI alignment and phylogenetic tree analysis were used to classify the 17 tested strains into three groups: C. tenuissimum, C. cladosporioides, and C. halotolerans respectively. The three representative strains(C1, C2, C12) caused maize leaf blight after 7 days post-inoculation. The wounded inoculations were of faster disease progression and lesion expansion. Re-isolation from lesion sites yielded the same inoculated strains. In conclusion, the maize-leaf blight pathogens in Hainan were C. tenuissimum, C. cladosporioides, and C. halotolerans, with C. tenuissimum being the dominant species; While C. cladosporioides was the pathogens which caused maize leaf blight in Jiangsu.

S435.131

兵团重点领域科技攻关项目(2024AB011)