Cotton RLP6 Interacts With NDR1/HIN6 to Enhance Verticillium Wilt Resistance via Altering ROS and SA.

Cotton Verticillium wilt (VW) is often a destructive disease that results in significant fibre yield and quality losses in Gossypium hirsutum. Transferring the resistance trait of Gossypium barbadense to G. hirsutum is optional but challenging in traditional breeding due to limited molecular dissections of resistance genes. Here, we discovered a species-diversified structural variation (SV) in the promoter of receptor-like protein 6 (RLP6) that caused distinctly higher expression level of RLP6 in G. barbadense with the SV than G. hirsutum without the SV. Functional experiments showed that RLP6 is an important regulator in mediating VW resistance. Overexpressing RLP6 significantly enhanced resistance and root growth, whereas the opposite phenotype appeared in RLP6-silenced cotton. A series of experiments indicated that RLP6 regulated reactive oxygen species (ROS) and salicylic acid (SA) signalling, which induced diversified defence-related gene expression with pathogenesis-related (PR) proteins and cell wall proteins enrichments for resistance improvement. These findings could be valuable for the transfer of the G. barbadense SV locus to improve G. hirsutum VW resistance in future crop disease resistance breeding.