Genome-Wide Association and Transcriptome Analyses Identify OsCBP606 as a Calmodulin-Mediated Susceptibility Gene to Magnaporthe oryzae in Rice

Rice blast, caused by the fungus Magnaporthe oryzae, is one of the most devastating diseases that affects rice production globally. Identifying new QTLs or R genes for blast resistance is crucial for developing rice varieties with enhanced resistance. In this study, a genome-wide association study (GWAS) to identify QTLs associated with blast resistance was conducted using phenotypic and genotypic data from 236 rice accessions. A total seven important QTLs linked to rice blast resistance were identified on chromosomes 1, 5, 6, 7, 10, and 12. Four main QTLs (qMZ6.1, qMZ7.1, qMZ10.1, and qMZ12.1) were key contributors to the blast resistance. Through combined analysis of differential expression and annotations of the predicted genes within qMZ12.1 based on haplotype and disease phenotype, we identified OsCBP606, which encodes a calmodulin protein, as the candidate gene for qMZ12.1. Compared with the wild-type plants, OsCBP606 knockout plants exhibited enhanced resistance to M. oryzae, while OsCBP606 overexpressing plants showed increased susceptibility. These findings highlight the critical role of OsCBP606 in modulating the rice immune response, making it a promising target for breeding programs aimed at improving rice blast resistance.