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

Rice blast is one of the three mian diseases in China. It's vary occurrence in rice producing areas in Hubei Province, especially has a high frequency, greater damage and causing economic losses in mountainous and hilly areas. The occurrence of the epidemic is impacted by the important factor such as resistance of rice varieties, geographical environment and climatic conditions, besides the inherent strength of Race composition and pathogenicity. Therefore, it's a great significance to definitude the physiological races, pathogenicity and geographical distribution of the rice blast fungus for the further study of the genetic diversity. It's very important to identify the anti-blast of rice varieties (lines) for rational use of resistant varieties, breeding disease-resistant varieties, and diseases control.The identification of Magnaporthe grisea Physiological Races and populations distribution in the major rice growing areas and rice blast often hair zone of Huber province based on the rice seedling stage in vivo and in vitro vaccination experiments, and identified population genetic structure of rice blast fungus by molecular biology Ways in these area, Defined Magnaporthe grisea genetic diversity From the molecular perspective. Identified the pathogenic of main rice blast fungus strains and analyzed disease resistance of parts of rice varieties (lines) in Huber Province for blast victims on this basis.It is providing a scientific basis to control rice blast and layout varieties areas as well as cultivate new varieties of the main research results are as follows:1. Identification and analysis of the Physiological Races of Rice Blast FungusFrom the identification of 89 isolates in 2007 and 2008, there were 6 populations 20 races in addition to ZD group in the counties of Huber province by testing 89 isolates and using distinguish host of China. Their dominant group is ZB, frequency is 55.1%, the frequency of ZA comes to 20.2% following it. Their dominant races are ZB31, Frequency is 20.22%, the frequency of ZG1 and ZB15 also follow it, come to 13.48% and 8.99%, they belong to the group of indica races. Structures of the rice blast fungus populations in the different area were obviously dissimilar. The highest frequency of other races does not exceed 6% at the same time. The distributions of races are relatively abundant in the junction of mountains and plains also called hills, there are thirteen race in four groups. And most of them are the indicate hills environment is also suitable for rice blast happened. The distribution of races in regions is closely related to the types of rice varieties, farming systems, geography and climate.2. Fingerprint analysisGenetic structures of 109 isolates of Magnaporthe grisea of Huber Province were analyzed by fingerprinting method from the molecular perspective, Divided them into 13 lineages, that the dominant is A5 at the level of 66.07%, and the composition of lineage A5 is the most complex one. The composition of dominant Lineage is more complex than the rare. The genetic structure of Magnaporthe grisea of mountain ecosystems is more diversity than the hills and plains, and there is a regular pattern that the change of population genetic diversity is the same with the composition of host variation. The results of fingerprint Determination is very different with the results of the identification of physiological race, but the fingerprint Determination is more stable.3. Pathogenicity analysis of Magnaporthe grisea.The pathogenicity of 53 isolates of Magnaporthe grisea mainly from combination of physiological races and the results of cluster analysis was analyzed by inoculation onto 49 rice varieties. Their pathogenic frequency (FP) varied greatly, from 19.6 1% to 70.59%. Their pathogenicity is related to the origins at same extent. Virulence of the isolates from Enshi area was the strongest with 50% PF, The general distribution can be classified by pathogenicity basically, and high pathogenic isolates distributed in the every lineage distinctively. The pathogenic of isolates from northwest of Huber are highly and various, distributed from high to low lingages of pathogenic. From the north to east and southeast are followed, but they also distribute in every lingages. The middle and weak isolates mainly distribute in the central, plain and lake area. Distribution of various types of pathogens may have a certain relationship with local geographical conditions and environment.4. Identification of blast resistance among Rice varietiesThe resistance of 49 varieties (lines) mainly from Hubei province was analyzed by inoculated with 53 magnaporthe grisea, their resistance frequencies (RF) are also varied greatly, between 37.74% and 77.36%. Fingerprint analysis showed that the phenotype response of Rice varieties(lines) to rice blast fungus is a concrete manifestation of the resistance mechanism, and the resistance mechanism of rice varieties(lines) may have a certain commonality. The Resistant frequencies of five New varieties, VE6208, Hua413, Aichuanxiang29B,T1007 and VE6223 are in the highest resistance sub-lineages, accoding to the RF, VE6208, Hua413, Aichuanxiang29B are the best varieties that can be applied to actual production.