Association analysis of rice resistance genes and blast fungal avirulence genes for effective breeding resistance cultivars.

Utilization of rice blast-resistance () genes is the most economical and environmentally friendly method to control blast disease. However, rice varieties with genes influence the outcome of genetic architectures of (), and mutations in avirulence () genes of may cause dysfunction of the corresponding genes in rice varieties. Although monitoring and characterizing rice genes and pathogen genes in field populations may facilitate the implementation of effective genes, little is known about the changes of genes over time and their ultimate impact on pathogen genes. In this study, 117 main cultivated rice varieties over the past five decades and 35  isolates collected from those diseased plants were analyzed by PCR using gene-specific markers of the nine genes and six primer pairs targeting the coding sequence or promoter of genes, respectively. The genes , , , , , and were identified in 5, 0, 1, 4, 18, 0, 2, 1, and 0 cultivars, respectively. Significantly, none of these genes had significant changes that correlated to their application periods of time. Among the four identified genes, had the highest amplification frequency (97.14%) followed by (51.43%) and (48.57%); had the lowest frequency (28.57%). All these genes except had 1-2 variants. Inoculation mono-genic lines contained functional genes of and loci with 14 representative isolates from those 35 ones revealed that the presence of certain , variants, and in populations, and these variants negated the ability of the corresponding genes to confer resistance. Importantly, and conferred broad-spectrum resistance to these local isolates. These findings reveal that the complex genetic basis of and some effective blast genes should be considered in future rice blast-resistance breeding programs.