江西省稻瘟病菌的致病性分化

Pathogenicity differentiation of Magnaporthe grisea (Hebert) Barr. from rice in Jiangxi Province of China

应用30个水稻抗稻瘟病近等基因系或单基因系及7个中国鉴别寄主,于水稻苗期接种,测定2006—2008年从江西省水稻产区分离的195个稻瘟病单孢菌株的致病性。结果表明,江西省稻瘟病菌以广谱致病性的菌株为主,将致病率按PF<30%、30%≤PF<50%、50%≤PF<70%和PF≥70%4区段划分,各区段菌株所占的比例分别为0、8.72%、31.28%和60.00%;病菌群体对所测定的30个抗瘟基因均表现出毒性,毒力频率为17.95%～100%,表现出较低毒力频率的水稻抗瘟基因是Pi-zt、Pi-1(1)、Pi-z5和Pi-k,其毒力频率分别为17.95%、26.67%、27.46%和29.23%。此外,江西省稻瘟病菌含6群40个生理小种,在稻瘟病流行的2006年,主要的优势小种为ZB13和ZA1;在稻瘟病发生较轻的2007年和2008年,优势小种均为ZB15和ZB13。进一步分析表明,同一优势小种内的不同菌株存在明显的致病性分化,28个ZB13菌株对30个抗瘟基因的致病率为50.00%～96.67%,26个ZB15菌株的致病率为46.67%～86.67%。对ZB13与ZB15菌株的聚类分析发现,毒力频率相近的菌株致病相似性差异很大。

Pathogenicity of 195 Magnaporthe grisea （Hebert）Barr. single spore isolates from indica rice in Jiangxi during 2006 -2008 was measured against 30 rice blast monogenic lines at rice seedling stage. The results showed that most strains were broad-spectrum pathogenic, and the pathogens accounted for O, 8.72%, 31.28% and 60.00% respectively when the pathogenicity frequency （PF） of the pathogen was divided four sections, i.e. PF 〈30% , 30% ≤PF≤50% , 50% ≤PF 〈70% and PF≥70%. The strains population was virulent to all 30 rice blast monogenic lines, vinflence frequency （VF） ranged from 17.95% - 100% , and resistance genes Pi-z1, Pi-1 （ 1 ） , Pi-z5 and Pi-k received lower VF, i. e. 17.95%, 26. 67%, 27.46% and 29.23% respectively. The strains population could be divided into 6 groups, 40 physiological races according to 7 Chinese differential cuhivars. Most strains belonged to ZA and ZB groups, and the predominant races were ZB13, and ZA1 ,with the frequency of 17.65% and 11.76% respectively in the 2006 when the rice blast was in epidemic; and the race group and predominant races were similar over the years of 2007 -2008 when the disease was moderately-light occurred, most strains belonged to ZB group, the predominant races were ZB13 and ZB13. The different strains of the same predominant race existed obviously pathogenic differentiation. The PF of 28 strains belonging to ZB13 to the 30 rice blast monogenic lines was 50.00%- 96.67%, and the PF of 26 strains belonging to ZB15 was 46.67%-86.67%. Cluster analysis also showed that the pathogenic similarity existed in a great difference among the strains with similar PF. All the results revealed the diversity and complexity of the pathogenicity of the fungus in Jiangxi Province. Key words：