Identification of a DAMP receptor and its cognate peptide ligand in sweet potato (Ipomoea batatas)

Abstract Sweet potato (Ipomoea batatas) is an important tuber crop, but also target of numerous insect pests. Intriguingly, the abundant storage protein in tubers, sporamin, has intrinsic trypsin protease inhibitory activity. In leaves, sporamin is induced by wounding or a volatile homoterpene and enhances insect resistance. While the signaling pathway leading to sporamin synthesis is partially established, the initial event, perception of a stress-related signal is still unknown. Here, we identified a leucine-rich repeat receptor kinase (IbLRR-RK1) that is induced upon wounding and herbivory, and related to peptide-elicitor receptors (PEPRs) from tomato and Arabidopsis. We also identified a gene encoding a precursor protein comprising a peptide ligand (IbPep1) for IbLRR-RK1. IbPep1 represents a distinct signal in sweet potato, which might work in a complementary and/or parallel pathway to the previously described HypSys peptides to strengthen insect resistance. Notably, an inter-family compatibility in the Pep/PEPR system from Convolvulaceae and Solanaceae was identified.