Genetic Diversity In Magnaporthe Grisea Population And Identification Of Resistance Of Hybrid Rice Varieties And Parents To Blast In Hunan

The rice blast is one of important rice diseases,which distributes in rice area in the world.The development of excellent disease-resistant varieties should be economical and effective approach for blast management. Resistant identification is the most principal task in the course of developing superior varieties. 129 Blast isolates from Hunan mountainous area and hilly area were analyzed by Rep-PCR.For the purpose of choosing blast fungous isolates useful for resistant identification,the author analysed genetic diversity of magnaporthe grisea population and geological distribution by DNA fingerprinting.According to the results of resistant identification,the author analysed the resistance heritability between F1 hybrids and restorer and the resistant correlationship in order to richen the information of resistance inheritance and to provide reliable foundation of breeding disease-resistant varieties.1. At 72% similarity level,the 129 isolates which come from Anhua,Liuyang,Taojiang and You xian were grouped into 4 lineages,which were composed of 24 haplotypes.Of these lineages,L1 and L3 were as dominate lineages .H5,H6 and H7 were as dominate habplotypes. These results showed that there was rather heterogeneous and potential variation in the blast pathogen,and a close positive relationship between genetic diversity of pathogen population structure and the diversity of cultivar constitutions.2. Based on Rep-PCR fingerprinting cluster of the 129 isolates,the author chosed 24 isolates(representing for 24 Habplotype) for resistant identification. 1) The resistant heritability of leaf blast was high between Fl hybrids and restorers.The resistance of 86.9% of 84 Fl hybrids is higher than that of their parent restorers lines .The general combining ability of restorers line 1725-284 and 1216-1025 were good. 2) 79 new lines from YHASS and 29 cultivars from Hunan rice regional trial were examined for their resistance to leaf blast and panicle blast. There was positive correlation between leaf and panicle blast resistance and the precentage of correlativity was 73.1%.