|XING, JUNJIE - Hunan Hybrid Rice Research Center|
|PENG, ZHIRONG - Hunan Hybrid Rice Research Center|
|HE, QIANG - Hunan Hybrid Rice Research Center|
|SHU, FU - Hunan Hybrid Rice Research Center|
|ZHANG, WUHAN - Hunan Hybrid Rice Research Center|
|SUN, PINGYONG - Hunan Hybrid Rice Research Center|
|DENG, HUAFENG - Hunan Hybrid Rice Research Center|
|ZHANG, ZHEN - Zhejiang Academy Of Agricultural Sciences|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2016
Publication Date: 11/21/2016
Citation: Xing, J., Jia, Y., Peng, Z., He, Q., Shu, F., Zhang, W., Sun, P., Deng, H., Zhang, Z. 2016. Characterization of molecular identity and pathogenicity of rice blast fungus in Hunan province of China. Plant Disease. doi:10.1094.
Interpretive Summary: Disease resistance in rice depends on genes that recognize pathogen infection and can mount a timely defense response. Rice blast disease caused by Magnaporthe oryzae is the most damaging rice disease worldwide. Major plant resistance (R) genes (Pi genes) can recognize pathogen strains according to their corresponding avirulence (AVR) genes that then results in a resistance response. Unfortunately, pathogens can overcome endogenous disease resistance genes by evolving infection signals that escape plant detection. Many blast resistant hybrid rice varieties in Hunan province in China have lost resistance to M. oryzae. To identify new blast R genes that can be used to breed disease resistant varieties, 182 field blast isolates from several ecological districts of rice production areas in Hunan province were analyzed using genomic technologies and rice varieties that possess known combinations of 24 major R genes. A total of 28 races out of 182 were identified and were grouped into 20 different categories. The results suggest that Pi9, Piz5, Pikh, and Pikm are the most effective blast R genes for use in breeding for rice production areas in Hunan province.
Technical Abstract: Characterization of molecular identity and pathogenicity of the rice blast fungus benefits the deployment of effective blast resistance (R) genes. In order to identify blast resistance genes in rice producing areas where most of the hybrid rice is grown in Hunan province, 182 M. oryzae strains were purified from various ecological districts in Hunan province, and were analyzed with a Chinese differential system (CDS), repetitive element-based polymerase chain reaction (Rep-PCR), and the presence and absence of avirulence (AVR) genes by PCR amplification with AVR gene specific primers. Identified blast R genes were validated with 24 monogenic lines (MLs) carrying 24 major R genes. A total of 28 races of M. oryzae were initially identified with CDS. They were then classified into 20 distinct groups with Rep-PCR. AVR-Pia, AVR-Pib, and AVR-Pi9 were detected in more than 86.8% of the isolates suggesting that the corresponding R genes, Pia, Pib and Pi9 are effective. However, pathogenicity assays on 24 MLs demonstrated that the R genes, Pi9, Piz5, Pikh, and Pikm, were more effective with resistant frequencies of 91.6, 91, 87.9, and 87.3%, respectively; other R genes were between 15 and 72.9%. These findings suggest that AVR-Pia and AVR-Pib did not express in some of field strains. Taken together, the data suggest that Pi9, Piz5, Pikh, and Pikm are effective blast R genes in Hunan province.