Genetic Diversity Of Colletotrichum Gloeosporioides Causing Crops Anthracnose

Anthracnose is one of the most important plant diseases worldwide, which could seriously infect many crops, especially in tropical and subtropical regions. Colletotrichum gloeosporioides was the most important species of Colletotrichum Cda, which had extensive host range, brought serious economy loss to agriculture. 36 isolates causing crop anthracnose were collected from 21 host plants located 7 provinces including Sichuan, Guangxi, Hainan and so on. Based on morphological characters, 35 isolates were identified as Colletotrichum gloeosporioides, whereas only 1 isolate was identified as C. acutatum. With analyses of species-specific PCR RAPD and internal transcribed spacer (ITS) sequences, all molecular data supported morphologic species including those isolates from maize,bean and banana except for CG1 from yam( Dioscorea opposita Thunb) anthracnose.There were significant differences in culture and morphology, the level of molecular genetics, phythogenicity, vegetative compatibility and so on among isolates. There were obvious variation of the color of colonies, the arrange of the acerulus, the shape and size of conidia, the morphological character of appressorium and the growth rate of colonies among isolates. The data of RAPD and internal transcribed spacer (ITS) sequences revealed rich gentic diversity. Based on RAPD data, at similar level of 0.64, 28 isolates were clustered into 2 groups, whereas 64% isolates were classified into the advantage group.which included different pathotypes, hosts and geographic origins. The results also revealed no closely correlation between random amplified polymorphic DNA and phythogenicity, hosts, geographic origins. ITS sequence showed genetic variations within C. gloeosporioides population.All isolates (except for CGI) were inoculated on the fruits of apple, grape, pepper and bean, which could cause the typical anthracnose symptom. Three pathotypes: strong pathotype, middle pathotype and weak pathotype were observed among isolates. Similarly, no closely correlation was found between and pathogenicityhosts, geographic origins. Spontaneous mutants with deficiencies in enzymes participating in the nitrate metabolic pathway (nit mutants), which could not use nitrate as sole nitrogen source, were obtained by transferring C. gloeosporioides strains onto minimal media containing 1.5%KClO3 28 isolates were classified into 13 vegetative compatilbility groups (VCGs).The results preliminarily showed that there was significant VCG diversity within C. gloeosporioides. However no closely correlation was found between VCG diversity and hosts, geographic origin, phythogenicity, molecular data of RAPD, ITS sequences.