Analysis On The Avirulence Genes And Resistance Genes Of Magnaporthe Oryzae And Resistance Evaluation Of Rice Varieties In Hubei Province

Rice blast, caused by Magnaporthe oryzae, is the one of the most widespread and destructive fungal diseases, severely devastating the production of the rice. At present, the most economic and effective method to control the disease is to breed and to apply resistant varieties rationally. However, the breeding resistant cultivars will lose resistance in3to5years due to the diversity and highly variation of the races. Therefore, grasping the law of dynamic variety of Magnaporthe oryzae, evaluating the main rice varieties resistant to rice blast disease and deducing the resistance genotypes in various rice cultivars have significant impacts on the breeding resistant varieties and the rationally deployment of the resistant cultivars in Hubei Province.In order to better understand of the applicability of24resistance genes in Hubei Province, the24monogenic lines were assayed under the condition of natural induction in Enshi and Yichang experimental bases respectively, where were usually used as rice blast disease nursery. The result indicated that K8(Pi-kh)、K10(Pi-z5)、 K18(Pi-1)、K25(Pi-km) showed good resistance to both leaf blast and panicle blast in Yichang experimental base, then the resistance gene Pi-kh、Pi-z5、Pi-1、Pi-km can be applied in Yichang district. The monogenic lines cultivars K18(Pi-1)、K25(Pi-km) were highly resistant to rice leaf blast and rice panicle blast in Enshi nursery, which proved that the resistance gene Pi-1、Pi-km could be used and applied in Enshi district.The avirulent genes of200M. oryzae isolates in Enshi experimental base were indentified by using24monogenic lines which contained single resistance gene. The results indicated that the24avirulent genes were detected in2012and2013, and the occurrence frequency of avirulent genes in2013is higher than that in2012; the avirulent genes Avr-Pikm、Avr-Pikh、Avr-Piz5、Avr-Pil had higher occurrence frequency, which mean the rice cultivars containing the resistance genes of Pikm、 Pikh、Piz5、Pil could be applied in Enshi district. However, the frequency of the avirulent genes Avr-Pik、Avr-Pikp、Avr-Pita、Avr-Pit、Avr-Pib was less than10%, which revealed the resistance genes corresponding to these avirulent genes have already lost resistant against to rice blast and can not be used in Enshi district of Hubei Province.96rice varieties in Yichang nursery and100rice varieties in Enshi nursery were conducted with natural induction in two consecutive years. The results showed that in Yichang experimental base the rice cultivar Tianyouhuazhan had good resistance to blast, and the cultivar Wen229also showed good resistance to rice leaf blast but middle resistance to panicle blast. In addition, the rice varieties, such as Shenliangyou5814、Ejingnuo6、Huyou9803、Jingyou5138etc, showed stable resistance to rice panicle blast in two consecutive years. In Enshi experimental base, Quanyou527、Guyou527、Yixiang107etc showed high resistance to rice blast during2012-2013.Analysis on the resistance genotypes of80rice cultivars to rice blast was tested by22M. oryzae isolates inoculating the detached scratched rice leaf in vitro. The results revealed that only6cultivars could be deduced containing certain resistance genes among80tested cultivars,11cultivars may contain the known resistance genes. The other67cultivars proved significant difference with the standard reaction patterns of the identified isolates, suggesting these cultivars contained unknown resistance genes or the combination of these genes.