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The Race Structure of the Rice Blast Pathogen Across Southern and Northeastern China
Yaling Zhang1,2, Qiongle Zhu1, Yongxiang Yao1,3
1State Key laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Provincial Key Laboratory for Crop Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China.
Background:
Rice blast, caused by the ascomycete Magnaporthe oryzae (Mo), imposes a major constraint on rice productivity. Managing the disease through the deployment of host resistance requires a close understanding of race structure of the pathogen population.
Results:
The host/pathogen interaction between isolates sampled from four Mo populations collected across the rice-producing regions of China was tested using two established panels of differential cultivars. The clearest picture was obtained from the Chinese cultivar panel, for which the frequency of the various races, the race diversity index, the specific race isolate frequency, and the frequency of the three predominant races gave a consistent result, from which it was concluded that the pathogen population present in the southern production region was more diverse than that in the northeastern region. The four blast resistance genes Pi1, Pik, Pik-m, and Piz all still remain effective in the southern China rice production area, as does Pi1 in the northeastern region. The effectiveness of Pita, Pik-p, Piz, and Pib is restricted to single provinces. The distinctive resistance profile shown by the Chinese differential cultivar set implied the presence of at least five as yet unidentified blast resistance genes.
Conclusions:
The Chinese differential cultivar set proved to be more informative than the Japanese one for characterizing the race structure of the rice blast pathogen in China. A number of well characterized host resistance genes, in addition to some as yet uncharacterized ones, remain effective across the major rice production regions in China.
Insights
Understanding the race structure of Magnaporthe oryzae (Mo) is crucial for managing rice blast disease. The pathogen population in southern China exhibits greater diversity than in the northeast, with several resistance genes remaining effective.
Area of Science:
- Plant Pathology
- Genetics
- Agricultural Science
Background:
- Rice blast, caused by Magnaporthe oryzae (Mo), significantly limits rice yields globally.
- Effective disease management relies on understanding the pathogen's population structure and virulence factors.
Purpose of the Study:
- To characterize the race structure of Magnaporthe oryzae populations in China.
- To assess the effectiveness of known rice blast resistance genes against prevalent pathogen races.
Main Methods:
- Testing interactions between four Mo populations from China and two differential cultivar panels.
- Analyzing race frequency, diversity index, and specific race isolate frequency.
- Evaluating the efficacy of resistance genes Pi1, Pik, Pik-m, Piz, Pita, Pik-p, Pib.
Main Results:
- The pathogen population in southern China is more diverse than in northeastern China.
- Resistance genes Pi1, Pik, Pik-m, and Piz are effective in southern China; Pi1 is effective in the northeast.
- The effectiveness of Pita, Pik-p, Piz, and Pib is limited to specific provinces, suggesting the presence of at least five novel resistance genes.
Conclusions:
- The Chinese differential cultivar set is more effective for race characterization in China than the Japanese set.
- Several known and novel host resistance genes remain effective across major Chinese rice production regions, offering potential for durable resistance.
