Functional Identification of the Novel Haplotype of Avirulence Gene AVR-Pik in Magnaporthe oryzae

The variation of avirulence genes (AVR genes) in Magnaporthe oryzae always leads to the breakdown of resistance in disease-resistant rice cultivars. Therefore, the study on the variation mechanism of AVR genes in M. oryzae is of great guiding significance for the breeding and rational utilization of disease-resistant rice cultivars. In order to better understand the variation mechanism of AVR-Pik in M. oryzae, the variation of AVR-Pik locus in more than 100 field isolates of M. oryzae collected from all over the country was analyzed in this study, and a novel haplotype AVR-PikG was identified whose encoding product contains a previously unreported point mutation M58I. Further functional identification results showed that the strains expressing only Avr-PikG were virulent to all tested monogenic lines carrying different Pik alleles, while the strains expressing only Avr-PikD^M58I were all avirulent, which demonstrated that Avr-PikG could evade the recognition of all known resistance proteins encoded by different Pik alleles, but the point mutation M58I in Avr-PikG might not be associated with its successful immune evasion.