Population Structure Of Magnaporthe Grisea In Fujian Province And Blast Resistance Of Rice Cultivars

Rice blast disease, caused by Pyricularia grisea(Magnaporthe grisea), is a world-wide rice disease and a main factor impeding rice safe production in Fujian province. Breeding and planting disease-resistant cultivars are effective measures to control the disease. But these cultivars are often to lose their resistance after that they are extended in field, causing are the pathgon to produce easily complicated pathogenicity and mutates. Measures are taken to prevent resistant cuttivars from losing resistance and causing the epidemics of the plant disease, such as constitutional analysis of physiologic race, resistance monitoring of rice cuttivars, utilization of resistant cuttivars, and resistant identification of new cuttivars. Based on understanding the physiologic race constitution, distribution and variation dynamics of M. grisea populations, in Fujian province were analyzed, and the resistances of main cultivars were figured out, which would provide a theoretical basis and practical application for breeding resistant cuttivars and rational distribution of resistant cuttivars.The three identifying systems of nationally general physiologic race, CO39 and LTH near-isogenic lines (NILs) were used to identify the race population of M. grisea during 2003-2008 in Fujian province. The results showed that the ZB and ZC race populations were the principal race populations identified by the system of nationally general physiologic race, among which the ZB13 and ZC13 were the major physiologic races.134.1 and 135.1 were the major virulent types identified by CO39 NILs. While J76.2 and J70.2 were the major virulent types identified by LTH NILs. The races of blast disease had great diversity on the virulent types and constitution in Fujian province, with increasing diversity year by year. ZB was the dominant population identified by using the identification system of nationally general physiologic race, while the subdominant population of ZC during 2007 and 2008 was more frequent, which indicate that the population of blast disease is changing obviously in Fujian province.Resistant identification for main cultivars in Fujian against blast disease revealed that main cultivars showed obvious polarization of resistance and sensitivity to seedling blast, which had only one middle resistant type among the 29 identified main cultivars, while manly had middle resistance or middle sensitivity to leaf blast among the 18 identified main cultivars, among which 14 cultivars showed middle resistance or middle sensitivity. However, unoptimistic results on the cultivars against neck blast, were got.these were which had only six cultivars with resistance or middle resistance among 18 tested cultivars, contributing 33.33%, and the rest showed middle to high sensitivity, among which seven cultivars showed sensitivity or high sensitivity. The results indicated that the tested cultivars were gradually becoming the affinitive cultivars to blast disease in Fujian rice growing areas. Guyou 527, Jiafuzhan and Teyou 627 were still resistant, which could be used as the major cultivars in production.