云南省元阳县籼/粳型稻瘟病菌无毒基因Avr-Pia、Avr-Pita1和Avr-Pii多样性分析

为明确云南省元阳县籼/粳型稻瘟病菌中无毒基因的多样性及差异,采用接种鉴别品种方法和PCR技术对9株粳型菌株和21株籼型菌株中无毒基因Avr-Pia、Avr-Pita1和Avr-Pii的多样性进行分析。结果显示,30株稻瘟病菌菌株中无毒基因Avr-Pia、Avr-Pita1和Avr-Pii的平均出现频率分别为33.3%、76.7%和0,Avr-Pia、Avr-Pita1在籼型菌株和粳型菌株中的出现频率分别为4.8%和100.0%、66.7%和100.0%。Avr-Pia主要为存在/缺失的多样性,籼/粳型菌株对水稻品种Achiasahi(Pia)的致病率分别为100.0%和11.1%;Avr-Pita1可划分为3个类群,除菌株CH1195属于PO类群外,籼型菌株均属于J1类群,粳型菌株则属于J2/J3类群;籼/粳型菌株对水稻品种K1(Pita)的致病率分别为100.0%和0,且籼/粳型菌株Avr-Pita1蛋白序列在第83位和第192位氨基酸差异明显。Avr-Pii在30株稻瘟病菌菌株中均未检出,籼/粳型菌株对水稻品种Fujisaka No. 5(Pii)的致病率分别为100.0%和0。表明Avr-Pia和Avr-Pita1在粳型菌株中的出现频率高于籼型菌株且变异程度低,粳型菌株中可能存在其它无毒基因使其不能侵染Fujisaka No. 5。

Polymorphism analysis of Avr-Pia, Avr-Pita1 and Avr-Pii in indica/japonica-borne Magnaporthe oryzae isolates in Yuanyang County, Yunnan

In order to clarify the polymorphism and differences of avirulence genes in indica (IB)/japonica-borne (JB) rice blast fungus, the inoculation of differential varieties and PCR technique were performed to analyze the polymorphism and differences of Avr-Pia, Avr-Pita1 and Avr-Pii in nine JB isolates and 21 IB isolates from Yuanyang. The results showed that the average occurrence frequencies of Avr-Pia, Avr-Pita1 and Avr-Pii in 30 isolates of Magnaporthe oryzae were 33.3%, 76.7% and 0, respectively. The occurrence frequencies of Avr-Pia and Avr-Pita1 in IB/JB isolates were 4.8%, 100.0% and 66.7%, 100.0%, respectively. Avr-Pia mainly showed the polymorphism of presence/absence. The pathogenicity rate of IB/JB isolates against Achiasahi (Pia) was 100.0% and 11.1%, respectively. Avr-Pita1 could be divided into three groups:CH1195 belonged to PO group, and the other IB isolates belonged to J1 group; JB isolates were classified as J2/J3 group. The pathogenicity rate of IB/JB isolates against K1 (Pita) was 100.0% and 0, respectively. The Avr-Pita1 protein sequence had significant difference in the 83th and 192th amino acid positions between IB and JB isolates. Avr-Pii was not detected in the rice blast fungus of Yuanyang. The pathogenicity rate of IB/JB isolates against Fujisaka No.5 (Pii) was 100.0% and 0, respectively. The results indicated that the frequencies of Avr-Pia and Avr-Pita1 in the JB isolates was higher than those in the IB isolates, and the variation degree was low. Other avirulence genes might existed in JB isolates which resulted in their non-pathogenicity against Fujisaka No. 5.