Genetic Diversity Of Colletotrichum Spp. From The Leaves Of An Invasive Weed Eupatorium Adenophorum

Crofton weed(Eupatorium adenophorum Speng) have invased into Southwest of China, and imposed enormous costs on agriculture, forestry, fishes, and other human enterprises, as well as human health, or even causes ecological catastrophe. Currently, it is very necessary to control its spread. Recently, research workers demonstrated Colletotrichum spp. is one of the numerically dominant endophytic fungi isolated from the leaves of E.adenophorum.. Generally Colletotrichum is described as a pathogen of many plants, which has the potential to be biological reagents controlling spread of E.adenophorum. However, the understanding of genetic diversity and virulence of Colletotrichum spp. isolated from leaves of E.adenophorum are unclear. It is necessary to explore this issue for understanding the invasion mechanism and controlling E.adenophorum invasion.This study selected E.adenophorum populations from different regions of Yunnan. Sichuan, and Guangxi provience, and determined their similarities and differences in genetic diversity and pathogenicity. The conclusions are following:1. The Colletotrichum spp. of E.adenophorum varied greatly in genetic diversity. Totally184strains from leaf spots. healthy leaves of E.adenophorum and the surrounding plants were isolated. They can be divided into37and30kinds of haplotypes. respectively, based on ITS gene and P-tublin gene difference. These strains are phylogentically similar to Colletotrichum boninense, Glomerella septospora, C. gloeosporioides, G. cingulata, G. acutata, C. siamense, C. crassipes, C. acutatum, C. orchidearum, C. fructicola and C.cliviae.2. There is no obvious genetic differences among different regions, invasion history and different isolation sources of Collectotrichum spp..The molecular variation of Collectotrichum from different regions and sources was evaluated by using RFLP, ITS genes and β-tublin genes. The result shows that these strains are no significant genetic differences.3. Multiple genes approach is more suitable to study phylogenetic relationships of Collectotrichum than the single gene method. At the species level, we can not divide Collectotrichum precisely only by ITS gene or β-tublin gene. All strains can not be identified at species level even analysis of the combination of these two genes.4. The numerically dominant Colletotrichum spp. in leaves of E.adenophorum have no obvious geographic uniqueness and invasion of historical uniqueness.5. Foliar edophytic Colletotrichum spp. of E. adenophorum has stronger pathogenicity to leaves of E. adenophorum than those isolated from the disease leaves of E. adenophorum as well as other species.