A Molecular Identification and Resistance Evaluation of the Blast Resistance Genes in Japonica Rice in Northern China

Abstract

Rice blast is a fungal disease that seriously threatens rice production. It is of great significance to identify blast resistance genes and clarify their functions in rice varieties. In this study, 11 rice blast resistance genes in 80 Japonica rice varieties in northern China were investigated, including their resistance to rice blast. The results demonstrated that Pita, Ptr, Pib, Pik, and Piks were most widely found, accounting for 48.8, 48.8, 41.3, 20.0, and 18.8% of the tested varieties, respectively. Pi5-G2 at the Pi5 locus and Pik-G5 and Pik-G8 at the Pik locus were also commonly found, and these alleles accounted for 30.0, 10.0, and 3.8% of all the tested varieties, respectively. Pizt was identified only in two cultivars, and alleles Pi2, Pi9, and Pigm at the Piz locus on chromosome 6 were not detected. We found that Pi5 and Pita were relatively conserved, but the alleles of Pik were abundant. Besides Pik, Pikm, and Piks, we also found 10 new haplotypes, and Pikp and Pikh were not found in the japonica rice varieties in northern China. Among the tested varieties, 5 did not carry any of the tested genes, 30 carried only one blast resistance gene, 27 carried two, 14 carried three, and 4 carried four. The resistance of varieties carrying three or four resistance genes was better than those carrying none of the resistance genes or only one or two. There were no significant differences in the resistance characteristics among varieties from different provinces. Our study provided a reference for the molecular breeding of rice blast resistance.