Population Structure And Pathogenicity Of Monilinia In Shanxi Province

Brown rot is one of the most important diseases of fruits. It is a threat in fruit production and has caused huge economic losses worldwide. The causal pathogens of brown rot include Monilinia fructicola, M.fructigena and M.laxa. The aim of the study was to determine the population structure and pathogenicity of Monilinia in Shanxi.The diseased fruits were collected from 2011 to 2014. In the sampling process, we found that brown rot mainly occured in the orchards which management is extensive. It rarely occured in the orchards which management is elaborate and it also rarely occured on the bagged fruits. Ninety-three strains were isolated and identified by morphology and molecular methods. The pathogenicity of eighty-one isolates was determined.1. The morphological identification results showed that 69 isolates belonged to M fructigena,15 isolates belonged to M.laxa,3 isolates belong to M fructicola and 6 isolates could not be judged accurately by morphological charaters.2.93 strains were amplified by PCR using three specific primers of Monilinia such as ITS1Mfcl/ITS4Mfcl, ITS1Mfgn/ITS4Mfgn and ITS1Mlx/ITS4Mlx. The results indicated that 79 strains had single band with high specificity,7 strains had two bands.7 strains which could not be amplified effectively using specific primers were sequenced using universal primer ITS1/ITS4. The results of morphological identification and molecular identification showed 75 isolated strains were M.fructigena,15 strains were M.laxa and 3 strains were M.fructicola, accounting for 80.7%,16.1% and 3.2% of the tested strains respectively.3. All apples and pears inoculated with the tested 81 isolates developed brown rot symptoms while the control remained healthy. According to the results of lesions on apple, 23.5% strains were characterized as Type ? with strong pathogenicity,46.9% as Type ? with medium pathogenicity and 29.6% as Type ? with weak pathogenicity. Type ??Type ??Type ? accounted for 30.9%?50.6%?18.5% respectively on pear. There had differentiation in pathogenicity among stains isolated from different areas. Isolates with the same pathogenicity had different proportion in different areas.