Identification Of Molecular Markers Linked To Rot Resistance In Apple Branches

Ring rot disease, rot disease and early defoliation in apple are triple main diseases in China. Ring rot disease in appple damage mainly branches, trunks and fruits. With the attention to environmen by the public, Ring rot disease need to be controled urgently by non-chemical substances and resistance species need to be demanded urgently. So closely linked molecular marker with resistance genes are needed urgently.Five-year seedling plants " hongyu×jinguan " were researched as segregation population based on the natural incidence in the field of apple branches, and closely linked molecular marker with resistance genes wre searched uaing SSR and AFLP. Results as following:Resistant and susceptical bulks and segregation population were verified with SSR and bulk segregant analysis by 140 SSR primers combined with SSR molecular markers and BSA (Bulk Segregant Analysis) . The results show that 5 primers have polymorphism. the exchange rate on CH02a04 primer in plant is minimum for 6.5% which amplified a band of 450bp, so the SSR markers CH02a04 was considered linked with the resistance gene. And it was calculated to be 5.1cM away from the resistance gene. Fortunately,the markerswas located in chromosome 2 or 7.In order to find some molecular markers more closely linked with the resistance gene, AFLP analysis was then carried out. AFLP analysis show that 10 primer pairs have polymorphism in 256 primer pairs .And the exchange rate on primer pairs E-AG /M-GAC and E-AGG/M-CTT in plant are minimum for 6.5% and 8.0%, respectively, which amplified bands of 280bp and 110 bp, respectively. 2 primer pairs E-AG /M-GAC and E-AGG/M-CTT showed linkage relation with the resistance gene in 256 primer pairs. These 2 AFLP markers flanked the target gene and located 5.1 and 6.2 cM away from the resistance gene, respectively.AFLP marker E-AG /M-GAC linked to the resistance gene was successfully converted into a SCAR markerIn order to facilitate the practice of molecular marker-assisted breeding, which have high correct rate through the analysis to plants.To determined relationship between resisitance in ring rot disease and strains, level and vertical verification were tested and verified by SSR and SCAR in resistanse and suscepitible plants , the results showed that the credibility of molecular markers of 75% - 85%...