Detection and Evaluation of Blast Resistance Genes in Backbone Rice Varieties from South China.

Rice blast caused by the pathogenic fungus poses a significant threat to rice cultivation. The identification of robust resistance germplasm is crucial for breeding resistant varieties. In this study, we employed functional molecular markers for 10 rice blast resistance genes, namely , , , , , , , , , and , to assess blast resistance across 91 rice backbone varieties in South China. The results showed a spectrum of resistance levels ranging from highly resistant (HR) to highly susceptible (HS), with corresponding frequencies of 0, 19, 40, 27, 5, and 0, respectively. Yearly correlations in blast resistance genes among the 91 key rice progenitors revealed (60.44%), (50.55%), (45.05%), (32.97%), (4.4%), (2.2%), (2.2%), and (1.1%). Significant variations were observed in the distribution frequencies of these 10 resistance genes among these progenitors across different provinces. Furthermore, as the number of aggregated resistance genes increased, parental resistance levels correspondingly improved, though the efficacy of different gene combinations varied significantly. This study provides the initial steps toward strategically distributing varieties of resistant rice genotypes across South China.