Allele Minging Of Resistant Genes To Magnaporthe Oryzae

Rice blast caused by ascomycete fungus Magnaporthe oryze is one of the major diseases on rice. Breeding and deployment of resistance varieties conferred by major R genes are the most cost-effective and environment-friendly approach to control the disease. Hence, the identification of new blast resistance genes in rice has being one of the most important activities for rice breeding programs. Two blast resistance loci, Pik and Pi2, were found to harboring resistance genes which conferred satisfactory resistance to blast disease in most of the disease nurseries in China.32previously screened resistance varieties and breeding lines were also tested in three of these nurseries and most of them showed high/moderate resistance reaction. The detection of Pik and Pi2loci in these varieties and lines by PCR-amplification showed that the presence of Pik locus in16, Pi2locus in25, and both loci in10of these varieties and lines. Sequence analysis showed that Pikm was found in KY12, KY14and KY24, Pikh was detected in KY11and KY19, Pi2was detected in KY5, KY6, KY9, KY10, KY11, KY13, KY16and KY18. These varieties were not only resistant at Lin’an, but also shown the resistance at either Pujiang or Taojiang, where all the IRBL lines carrying these three known alleles were susceptible. The Pik-1and Pik-2protein sequences of KY15, KY23and KY28were distinct to the known alleles. The amino acids sequence of Pi2locus in KY3and KY14also formed a distinct out-group form the remaining cultivars in each subgroup.