Characterization of self-incompatibility genes in Brassica rapa var. toria and yellow sarson

Self-incompatibility (SI), a reproductive mechanism that prevents self-pollen from fertilizing the ovule, is widespread in flowering plants, including the Brassicaceae family, where it promotes outcrossing, genetic diversity, and hybrid vigor. Although prevalent in Brassica rapa, an economically vital crop, it remains poorly characterized in widely grown varieties, such as toria and yellow sarson, with prior studies primarily focused on Brassica napus. Given its potential for hybrid breeding and crop improvement in Brassica rapa, we characterized key SI-regulatory genes, analyzing their phylogenetic relationships, structure-function dynamics, and expression patterns. Our results indicate sequence, structural, and functional homology as well as conservation with previously known candidates. This study identified the integral role of the key players in regulating self-incompatibility and ROS dynamics. We identified SRK, FER, and ARC1 as essential for SI, while SRK, FER, and MLPK activated the ROS response. Our findings establish a foundation for harnessing this natural system to integrate agriculturally important traits and sustain them across generations via outcrossing.