Exploring, Genetic Analysis And Mapping Of New Blast-Resistance Gene In Rice

Rice blast,caused by Magnaporthe oryzae,one of the most important diseases inrice growing regions of the world,which usually leads to a sharp decline in riceproduction and even results in no yield. Breeding the broad-spectrum, highresistance blast varieties is important research direction for breeders.05CR131is a broad resistance restorer lines rice,showing great resistance tocollection of more than10kinds of rice blast fungus in south of China. Its geneticbackground and resistance gene have not been studied. In order to speed up thebreeding process, effective and rapid use of new resistance genes in these restorerlines,Exploring genetic analysis and mapping of new blast-resistance gene with05CR131.The results of this study are as follows:(1)The blast isolates selectionInoculation of31single gene lines containing rice blast resistant genes with9kinds of the blast isolates collected from the South China. The results of inoculationof sha xian Xia mao of fujian province in2009are consistent in Hainan in2010.Form the result of Inoculation the blast,we fine that GUY11has a good capacityof producing spores and pathogenicity,the pathogenicity frequency up to83.9%.(2)Allelism investigation of blast-resistant genes05CR131hybrid with single-gene lines containing broad-spectrum blastresistance gene pi-2,they are both resistance to the GUY11. Inoculated in the hybridoffspring F2generation injection, segregating populations appeared susceptiblemonoclonal. It's indicate that resistance gene in05CR131is different from thebroad-spectrum blast resistance gene pi-2, it maybe a new resistance gene.(3)Inoculation of the mapping populationThe two parents of05CR131,LTH and their F2population were inoculated withthe isolate GUY11of blast by Field injection inoculation and indoor sprayinoculation.Their phenotypes to the isolate GUY11were identified and the ratio of blast resistance to blast susceptible from F2population were counted. The resultsindicated that the ratio of blast resistance to blast susceptible from F2populationwas3:1according to single locus on Mendelian segregation, demonstrating that05CR131had one dominant resistant gene to the isolate GUY11of blast.(4)Selection linked markers of the resistance geneUse of136SSR markers uniformly distributed on rice12chromosomes,Thepolymorphism analysis were carried out between parents and pools (resistance andsusceptible) with136pairs of SSR markers evenly distributed in12chromosomes ofrice (Oryza sativa). The results demonstrated that there was a SSR marker RM166located on the2chromosome of rice showing the polymorphism between parents andpools (resistance and susceptible).With bulked-segregant analysis and recessive-classanalysis the blast resistance gene Pi-y(t) of05CR131was mapped between the markerRM12544and RM6378and their genetic distance to the blast resistance gene Pi-y(t)were5.1cM and1.5cM.