The Distribution Of Rice Blast Resistance Gene And Resistant Evaluation In Part Rice Cultivars In Zhejiang Province And Conventional Rice Varieties

Rice blast, which is caused by Magnaporthe oryzae, is one of the major diseases of rice. The occurrence of rice blast may significantly reduce the yield and quality of rice. Currently, the use of resistant varieties is the most economical and effective measure to rice blast. The selection and breeding resistant rice varieties have an outstanding result, but there has been recession. Numerous studies demonstrate that the variation of pathogenic and enrichment of specific race are the main reason for recession of blast resistance. By the rational distribution and rotation of resistant varieties, it can avoid the rapid decline of rice variety blast resistance, ease the pressure of exploring new sources, and extend current cultivars disease resistance in production life. While the key of guiding rational distribution of rice varieties is the blast resistance genotype of cultivars. Thus, it is significant for breeding disease-resistant varieties and extending its resistance to study anti-blast genotypes of cultivars.So far, the identification of rice blast resistance is still stay in the identification of rice varieties resistant phenotype in China. But with the cloning of blast resistance gene, there has developed a large number of molecular markers that tightly linked to blast resistance genes, especially from some resistance gene sequence itself, which bring a new opportunity for identifying fast, accurate and systematic genotypes of rice blast resistance and conducting efficient resistance gene pyramiding. Molecular identification, an important complement to traditional resistance identification, and tranditional resistance identification combine reasonable that can achieve the purpose of sustained and effective control to rice blast.In the study, the sequence of 9 isolated rice blast resistance gene and the corresponding LTH NILs were applied to establish an identification system about resistance gene. Then, 24 LTH NILs and 68 culativars were tested the blast resistance gene by using the established system. Meanwhile,7 and 12 strains from each representative Rice in Zhejiang province were especitively used for identifying 24 LTH NILs and 68 cultivars and evaluating their potency. The following is a brief introduction of the relevant research, the results and significance of these studies:1 In the experiment, there were 117 pairs of specific primers that were designed for 9 rice blast resistance gene after the verification by PCR amplification.2 The blast resistant identification of LTH monogenic lines showed that there are 11 varieties whose onset of the average level reached nine, only 5 varieties below the level four. The evaluation of blast resistance indicated that only B6 (Pikh), B8 (Piz5), B9(Pizt), B10 (Pita) and B12 (Pit) are resistant varieties, the other 19 belong to the susceptibale varieties. There were significant differences among varieties by using DPS software for statistical analysis and Duncan s new multiple range method for multiple comparison of blast resistance. And B9 (Pizt) perfroms the strongest blast resistance, LTH performs the weakest.3 The blast resistant identification of varieties concluded that there are 4 varieties whose onset of the senior level reached nine,34 varieties s more than 6,34 varieties s in five or less,and 20 varieties s in two or less. And 4 varieties are not sick. The evaluation of blast resistance indicated that there are 22 lines belonging to high resistant varieties,12 belonging to middle resistant and 5 belonging to susceptible. Xiushui 09, Zhejing 88, Zhongzheyou 8, Youyong 12 and Yongyou 15 perform the strongest resistance, and Yongyou 9 performs the weakest.4 The test of cultivars s genotype showed that there are 16 varieties which carry 5 resistance genes,8 varieties carry 6,5 varieties carry 7,6 varieties carry 8 at the same time, and only 2 varieties carry 1 resistance gene. It is intereating that Xiushui 09, Zhejing 88, Zhongzheyou 8, Yongyou 12 and Yongyou 15 which showed the most resistant in all varieties all carry blast resistance genes Pib, Pizt and Pikm.