Pathogenicity differentiation of Dioscorea opposita Thunb. anthracnose pathogen in southern China

ObjectiveThe pathogenic bacteria species of Dioscorea opposita Thunb.anthracnose in southern China and pathogenicity differentiation were studied to provide reference for comprehensive control of D.opposita anthracnose and disease resistant varieties breeding.MethodForty-five strains of pathogenic bacteria were isolated from D.opposita leaves with typical anthracnose lesions collected from six provinces(Sichuan,Guizhou,Yunnan,Guangxi,Fujian,and Hainan)in southern of China.These strains were identified by morphological observation,rDNA-ITS sequence and phy-logenetic tree analysis.Pathogenicity of them were tested by inoculating four D.opposita gerplasms(Do6-3,Do6,Do108 and Do21)on the leaves,then the pathogenicity strength of strains with various sources were analyzed.ResultAll 45 strains were identified as Colletotrichum gloeosporioides. They were all pathogenic to the four D. opposita gerplasms. These strains were classified into three groups based on their comprehensive pathogenicity.Six highly pathogenic strains came from Guangxi,seven weakly pathogenic strains mainly came from Yunnan,thirty-two moderately pathogenic strains mainly from Guizhou,Fujian and Hainan.ConclusionThe 45 D.opposita anthracnose pathogenic bacteria from six provinces(autonomous region)in southern China are identified as C.gloeosporioides.The pathogenicity differentia-tion of them are obvious and related to geographical origin.