Resistance Evaluation And Genotype Deduce Of Several Hybrid Rice Parents To Rice Blast

Rice blast disease which is caused by Magnaporthe grisea is one of the three major deseases of rice, infecting the quantity and quality of rice crops all over the world. It has been proved that breeding and utilizing disease-resistant cultivars is the most economical, secure and efficient means to control rice blast disease. In hybrid rice breeding, the resistance to blast of hybrid rice combinations are influenced by sterile and restorer lines, but the breeding of sterile line is very difficult, and the resistance of male sterile line is poor. Therefore, the main strategies of breeding hybrid rice of resistanting rice blast is increasing the rice blast resistance of restorer and maintainer lines.In this study, the resistance to rice blast of100rice prarental varieties(50maintainer lines and50restorer lines) were indentified by field-induced identification technology from year2009to2011at Caoba Ya’an; the spectra to blast disease of77rice prarental varieties were tested by spray inoculation methed using80single spore isolates of Magnaporthe oryzae isolated from different samples which were collected in Sichuan province in year2011; the genotype to blast disease of these varieties were deduced by inoculating22differentiated isolates of M. oryzae of different spectra to24lines of whice each had a single, different, known resistance gene.The results were as follows:1The results of field resistance identification show that:the resistance of the same variety in differert years was slightly different in the three years; the leaf and panicle blast disease of the same variety in the same year showed a certain correlation, but there was a little differences among some varieties. The maintainer lines of which panicle blaste was immunization were only two materials, accounting for4%of these tested maintainer lines; The maintainer lines of which panicle blaste performed9grade and the grade of leaf blast were from5to9were22materials, accounting for44%. The restorer lines of which panicle blaste was immunization were10materials, accounting for20%of these tested restorer lines; The restorer lines of which panicle blaste performed9grade were few, there were only two materials in the identification results in year2009.2The results of testing the resistance spectra showed that:among the34maintainer lines,2varieties of resistance frequency were among40%to60%, accoutiong for5.89%of the tested maintainer lines;10varieties of resistance frequency were among60.01%to70%, accoutiong for29.41%;12varieties of resistance frequency were among70.01%to80%, accoutiong for35.29%;8varieties of resistance frequency were among80.01%to90%, accoutiong for23.53%;2varieties of resistance frequency were more than90%, accoutiong for5.89%. Among the43retorer lines, only1varieties of resistance frequency was less than80%;16varieties of resistance frequency were among80%to90%, accoutiong for37.21%;26varieties of resistance frequency were more than90%, accoutiong for60.47%.3The results of deducing the genotype to blast disease showed that:among the50tested maintainer lines,26varieties could be derived may contain resistance genes, accounting for52%; there had been9resistance genes among these26materials, such as pik, pia, pil9, pi5, piks, pish, pikp, pill, pi7, of which, the most occurrence frequency of these resistance genes was pik and pia; cluster analysis(threshold=0.85) for the tested maintainer lines, all of them could be classified6categories according to their resistance performance. Among the50tested restorer lines,24varieties could be derived may contain resistance genes, accounting for48%; there had been8resistance genes among these24materials, such as pik, pia, pi12, pish, pikp, pi7, pii, pi3, of which, pik and pia also were the most occurrence frequency; cluster analysis(threshold=0.70) for the tested maintainer lines, all of them could be classified9categories.