Studies On The Pathogenicity Of Rice Blast Fungus And Improvement Of Blast Resistant Varieties Of Rice In Heilongjiang Province

The rice blast pathogen, Pyricularia oryzae, is one of the most devastating rice diseases, Occurred in every rice producting areas of the world. Heilongjiang Province is the important japonica rice grown regions in China, In recently years, The extension of monoculture cultivars across large scales enhanced directional selection pressure for blast pathogen populations, Caused rice blast happened seriously every few years in Heilongjiang Province, and losses large scales yield. The breeding and application of rice blast resistant varieties is the most economical, safety and effective way to manage blast disease. But there are not enough rice blast resistance resource in Hei longjing provice, So it is necessary to introducing more blast resistant genes into cultivars. Understanding pathogenicity of rice blast pathogen, Analysis the comparison and distribution of avirulence genes in different times and different regions and the spectrum of rice blast resistant genes, and study blast resistant genes in the sime time, Which is the same significant when deploying cultivars carrying different resistance genes and breeding new resistant varieties. In order to know the pathogenicity of rice blast fungus and distribution of the avirulence genes in defferent years and different regions and the spectrum of rice blast resistant genes in Heilongjiang Province, In the same time to improving resistance of japonica rice varieties to blast disease and broaden the blast resistance resources through intruducing new rice blast resistance genes, Over the years we have done the following 3 aspects of the study1. Identification of Magnaporthe grisea pathogenicity and research on spectrum of rice blast resistant genes in Hei longjiang ProvinceThe rice blast pathogen, Pyricularia oryzae, was collected from thirteen cultivars come from six regions of rice grown consist of twenty three counties or farms in 2010,2012 and 2013 years, Sixty-three single spore isolates be divided and studied against thirty-one rice varieties known resistance genes to undstanding pathogenicity of Magnaporthe grisea and the spectrum of rice blast resistant genes in Hei longjian province. The result indicated that:(1) The pathogenicity of rice blast fungus in Heilongjiang province 31.7% of isolates had the strong pathogenicity,46.0% of isolates had relative strong pathogenicity,22.2% of isolates had moderate pathogenicity. (2) The resistance gene Pi9, Pita-2(R), Pi-z5(CA), Pi-12(t) and Pi-ta2 (P) had relatively broad spectrum resistance from74.6% to 93.7% for rice blast fungus in Heilongjian province, It suggested that these blast resistance genes have a great of usability in rice blast resistance breeding. These resistance genes Pia (A)?Pit?Pish (B)?Pi7(t) and Pi19(t) had a low resistance spectrum from4.8% to 19.0%, these genes apply in rice blast resistance breeding be careful.2. Introgression Pi-1?Pi-2 and Pi-33 to improve the blast resistance of Kongyu 131To improve the blast resistance of Kongyu 131, using backcrossing and molecular marker assisted selection (MAS) technology, three rice blast resistance genes (Pi-1, Pi-2 and Pi-33) from indica variety Zhongjin 23 were introgressed into Kongyu 131.28 Kongyu 131 introgression lines with different rice blast resistance genes were obtained. Among them, the k165?k166 and k191 with three resistance blast genes(Pi-1, Pi-2 and Pi-33), respectively, were possess of 98.4% resistance frequency to different blast race, which significantly higher than carrying 1 and 2 resistance blast gene lines, and the comprehensive agronomic traits of k165 line were same as Kongyu 131. It suggested that these rice blast resistance genes have a great useful in Heilongjiang province. These introgression lines could be used to breeding for rice blast as blast resistance resources, and could be applying on rcie producting directly.3. Pigm introduction and progeny resistance and yield identificationThrough the combination of marker-assisted selection (MAS) and hybrid breeding, the broad-spectrum blast resistance gene Pigm from Gumei4 (indica) was successfully introgressed into Kong Yu131, Long Jing26 and Ken Jiandao 6,12 contained Pigm gene introgression lines were obtained. Compared with recipient parent, the blast resistance of introgression lines have greatly improved, which the resistance frequency up to 98.4% and a minimum of 95.2%. At the same time, panicle blast resistance is also improved, after introgessed Pigm gene, Kongyu 131 panicle blast from 7 to 1 level, Longjing 26 panicle blast from 5 increased to 0-1 level, kenjiandao 6 panicle blast by 7 increased to 1-3 level.Kongyu 131 was introgressed Pigm gene, that the grain number per spike was increased, but seed setting rate became lower, So that the yield difference was not significant, The decrease of seed setting rate offset the effect of the increase of grain number per ear on the yield increase. Longjing 26 introduction of Pigm gene, that the grain number per spike was increased, and seed setting rate decreased, Only one introgression line k121 grain yield increased significantly. Ken jiandao 6 after introgressed Pigm gene, the effective panicle number and seed setting rate were all decreased, The contribution of grain number per ear to yield was more than the effect of effective panicle number and seed setting rate, So the yield per plant increased significantly. Thus it can be seen, the recipient parent selection is important to improving rice blast resistance of japonica rice in cold region.