Multiple BnaSOBIR1-Associated Receptor-like Proteins Contribute to Enhanced Resistance to Sclerotinia sclerotiorum in Brassica napus L. (Oilseed Rape)

As a major fungal pathogen of Brassica napus, Sclerotinia sclerotiorum causes significant yield reductions worldwide. Receptor-like proteins (RLPs) are essential components of plant immunity, but the functions of many RLPs in B. napus still remain unclear. In this study, three BnaSOBIR1-interacting leucine-rich repeat RLPs (LRR-RLPs), named BnaRLP-G13-2, BnaRLP-G13-3, and BnaRLP-G13-4, were identified by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Promoter analysis revealed diverse cis-acting elements involved in stress and phytohormone responses. Overexpression of these genes significantly improved resistance to S. sclerotiorum in both Arabidopsis thaliana and B. napus. Consistently, BnaRLP-G13-2/3/4 restored disease resistance and NLP-induced ROS production in the rlp23-1 mutant. Furthermore, BiFC assays suggested an association between BnaRLP-G13-2/3/4 and Ssnlp24SsNEP2-associated perception, although direct biochemical binding remains to be demonstrated. These findings advance the understanding of BnaSOBIR1-associated BnaRLP-G13-2/3/4-mediated immunity and provide new insights into enhancing disease resistance in oilseed crops.