Improving Blast Resistance Of Key Sterile And Restorer Lines In Rice Through Molecular Marker-assisted Selection

Rice blast,as one of the most serious diseases in rice production,causes different degrees of damage to Chinese rice production every year.breeding resistant varieties is the most effective way to control rice blast.In this study,the broad-spectrum blast resistant genes?Pigm?and?Pi40?genes of Gumei 4 and IR65482 were introduced into the mainstay parents C815S,Chuang 5S and restorer lines Huazhan and R4418 by backcross breeding and molecular marker-assisted selection?MAS?.The rice blast resistance and the main agronomic traits of the male sterile lines and restorer lines which were successfully introduced into the resistant genes were identified and evaluated comprehensively.The main results were as follows:1.Two stable molecular markers,namely:RM7311 and RM527,with significant polymorphism between Gumei4?IR65482 and donor parents,were selected,and the resistant genotypes between recipient and donor parents were identified.2.In backcross breeding,the resistant genotypes were selected by molecular markers closely linked to resistance genes in each generation,and homozygous lines carrying Pigm and Pi40 genes were obtained respectively.3.The BC₃F₂ homozygously improved lines were used to identify the resistance to rice blast in the field.The results showed that the blast resistance of the recipient parents were medium susceptible,the lines were medium resistance and resistance.the some lines was similar to the donor parents.4.The main agronomic traits of BC₃F₂ homozygously improved lines were investigated.The results showed that the improved lines basically retained the excellent characters of the recipient parents,except that part of the BC₃F₂ plant with panicle length and number of panicles per plant ect,than that of the receptor parents.