Study Of The Genetic Laws Of Scab-resistant And The Molecular Makers Of AFLP In Pear

Pear trees are almost growing in all temperate regions, it is also one of the main tree species in China. Pear scab has always been the main disease which affects the pear industry development over the years, its infect objects are commonly pear fruits and leaves, moreover, the disease spreads fast, and disease prevention is difficult, so it will spawn a great number of economic loss in the disease prevalent year. The cycles traditional methods of breeding disease-resistant varieties are too long, they could cause time and manpower consuming, thus they can’t satisfy the requirements of production. Take advantage of the DNA molecular maker technology which is convenient and highly accurate assists breeding, by looking for the molecular makers which closely link to the scab-resistant gene, and use them to identify pear trees in seeding stage, it can greatly improve the efficiency of the disease-resistant breeding.In this study, the disease-susceptible cultivar(Yali) and the disease-resistant cultivar(Jin’ershi) were used as the parents, we had analyzed the parents and their140hybrid seedlings of F1generation by AFLP molecular maker technology, in order to find the molecular makers linked to the genes of pear scab-resistant. The results are as follows:1. We surveyed the infection situations of individuals of F1generation by the way of artificial inoculation pathogen. The results showed that in all of the140seedlings, there were38scab-susceptible plants and103scab-resistant plants, checkout by the chi-square, Chi-square test Χ2=0.346<x2(df=1,0.05)=3.84, the segregation ratio between susceptible and resistant plants was1:3, the results conformed to the ’two way-Pseudo-testcross’theory.2. A AFLP analysis system suitable for pear leaves was established:20μL enzyme system, in which the DNA of leaves3μL, two kinds of enzyme(EcoRI/MseI)3U, respectively; enzyme digestion time3h; connection time was commonly10h,it can also be used for the night; connection and pre-amplification products should be used after diluted10times; the products of selective-amplification needed to heated up at95℃for10min, at last the products would be detected by7%polyacrylamide gel electrophoresis.3. We filtered from64pairs of primer combinations by the method of BSA, the results showed that there were12pairs of primer combinations with high resolution and their polymorphism were better, and we got a molecular marker(S-305) linked to the gene of pear scab-resistant from one primer combination(E-AGC/M-CTT). The genetic distance between this molecular marker and the gene of pear scab-resistant was8.4cM.