Genetic Diversity Of Monilia Yunnanensis By Using RAPD Analysis

Brown rot disease caused by Monilinia spp. is an economically important fruit disease worldwide. So far, researches about brown rot diseases in China are mainly focused on peach but not on other fruit trees. This work aimed to estimate the genetic diversity within different isolates of M. yunnanensis and evaluate the influence of environments and fruit tree cultivars by using random amplified polymorphic DNA(RAPD) technology. The 422 isolates of M. yunnanensis from Yunnan province and Beijing city and the five hosts of M. yunnanensis are peach, plum, apricot, apple and pear.(1)A total of 34 RAPD polymorphism fragments were generated which size ranged from 0.4 to 3.0 kb by 19 selected primers. The reproducibility of the results was confirmed by repeating the RAPD-PCR analysis with 422 randomly selected isolates. The number of reproducible bands produced by each primer ranged from 1 to 11 polymorphism bands per primer.(2) The dendrogram showed significant clustering of the isolates from same hosts according to their geographical origin, which indicated that almost all of M. yunnanensis in the same place were clustered into one group, no matter from which host species. The Similar results were obtained through estimate genetic distance and genetic identity of strains in different places. Results showed that isolates from same place have a closer genetic relationship.(3) The phylogenetic trees showed that isolates from different host plants in the same area tended to group together, such as all of the strains from peach were clustered together and group two contained most of strains from peach and pair, indicating that the cultivars had an important impact on the fungal population. Peach is an important resource of stone fruits, while pear and apple belonging to pome fruits, so the strains from stone fruits and the strains from pome fruits are closely related phylogenetically.(4) Due to the strains from different host species, all of 422 M. yunnanensis strains were divided into five groups. Apricot is one of the stone fruits, while pear and apple are important resource of pome fruits. In the UPGMA-based dendrogram, indicating that the samples under the same species were clustered together, so the strains from apple and pear in relationship were near with each other while they were far with the strains from apricot. The values of genetic distance and Nei’s genetic identity showed that isolates from some regions in Yunnan province had a closer correlation, but had minor correlation with that from Beijing.