Candidate Gene Discovery for Rust Resistance Through Multi-Locus Genome-Wide Association Study in Groundnut

Rust, caused by Puccinia arachidis, is one among the most destructive fungal diseases constraining global groundnut (Arachis hypogaea L.) production. While the development of disease-resistant varieties stands as the most effective approach to preventing substantial yield losses, the genetic mechanisms underlying resistance to rust is not yet well understood, emphasizing the necessity for further detailed research. In this study, 184 accessions from the ICRISAT groundnut mini-core collection were evaluated for rust resistance at Dharwad, India, across multiple seasons, as well as in Vietnam for one season. Whole-genome resequencing-based genome-wide association study (GWAS) identified five highly significant marker trait associations (MTAs) for rust resistance (p = 5.22 × 10-13 to 7.21 × 10-08). Among these, two robust rust-associated kompetitive allele specific PCR (KASP) markers, snpAH00607 at chromosome Ah01 and snpAH00609 at chromosome Ah17, were validated across diverse set of breeding and pre-breeding lines. These markers were linked to candidate genes encoding sterol C4-methyl oxidase 1-2, implicated in brassinosteroid-mediated salicylic acid signalling, and MYB transcription factor known to be associated with defense responses. The identified SNPs, validated markers, and candidate genes will serve as important resources for marker-assisted breeding of rust disease resistant groundnut varieties.