南方稻区稻瘟病菌株中无毒基因AvrPi9的变异分析

Variation analysis of avirulent gene AvrPi9 in the Magnaporthe oryzae field isolates from rice-producing areas of southern China

本研究通过PCR(Polymerase Chain Reaction)和测序技术以及稻瘟病菌致病力检测手段,分析了2020年来自安徽、重庆、福建、广西、湖南、江苏、江西、云南以及浙江等省(直辖市、自治区)的300个稻瘟病分离菌株的无毒基因AvrPi9的分布和变异情况。结果表明,298份稻瘟病菌分离菌株的AvrPi9位点能被有效扩增,扩增产物经测序分析后显示,其中8株供试菌株的AvrPi9基因位点的外显子区域253位发生单碱基变异(C碱基替换成T碱基,AvrPi9^(C253T)),导致转录提前终止。稻瘟病菌致病力分析表明,AvrPi9^(C253T)菌株对带有Pi9基因的植株TP309-Pi9产生了致病性,说明该类菌株的AvrPi9位点变异后不能被Pi9识别。上述结果提示培育和种植携带有抗稻瘟病基因Pi9的品种可以较大程度上对南方稻区稻瘟病起到防控作用。这对保障水稻生产安全具有重要意义。

In this study, PCR(Polymerase Chain Reaction), sequencing and rice blast pathogenicity detection were used to analyze the distribution and variation of the avirulent gene AvrPi9 in 300 Magnaporthe oryzae field isolates, which were collected form Anhui, Chongqing, Fujian, Guangxi, Jiangxi, Jiangsu, Hunan, Yunnan and Zhejiang provinces in 2020. The results showed that the AvrPi9 locus of 298 isolates could be amplified effectively. A variation(cytosine replaced by thymine, AvrPi9^(C253T)) in the exon 253 of AvrPi9 gene locus from 8 isolates, which resulted in frameshifts with premature termination by introducing stop codon. The pathogenicity analysis showed that the AvrPi9^(C253T) strain caused disease in the transgenic plant TP309-Pi9, indicating that the AvrPi9^(C253T) in this strain could not be recognized by Pi9. These results suggested that breeding and planting rice varieties carrying rice blast resistance gene Pi9 has scope for prevention of rice blast in rice-producing areas of southern China.