A Small Cysteine-Rich Protein Triggers Immune Responses in Diverse Plant Hosts.

The oomycete is a necrotrophic pathogen that infects many crop species worldwide, including ginger, soybean, tomato, and tobacco. Here, we identified a small cysteine-rich protein, PmSCR1, that induces cell death in by screening small, secreted proteins that were induced during infection of ginger and did not have a predicted function at the time of selection. Orthologs of PmSCR1 were found in other species, but these did not have cell death-inducing activity in . encodes a protein containing an auxiliary activity 17 family domain and triggers multiple immune responses in host plants. The elicitor function of PmSCR1 appears to be independent of enzymatic activity, because the heat inactivation of PmSCR1 protein did not affect PmSCR1-induced cell death or other defense responses. The elicitor function of PmSCR1 was also independent of BAK1 and SOBIR1. Furthermore, a small region of the protein, PmSCR, is sufficient for inducing cell death. A pretreatment using the full-length PmSCR1 protein promoted the resistance of soybean and to and infection, respectively. These results reveal that PmSCR1 is a novel elicitor from , which exhibits plant immunity-inducing activity in multiple host plants. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.