Novel EIicitin from Pythium oligandrum Confers Disease Resistance against Phytophthora capsici in Solanaceae Plants.

The mycoparasite Pythium oligandrum is a nonpathogenic oomycete that can boost plant immune responses. Elicitins are microbe-associated molecular patterns (MAMPs) specifically produced by oomycetes that activate plant defense. Here, we identified a novel elicitin, PoEli8, from P. oligandrum that exhibits immunity-inducing activity in plants. In vitro-purified PoEli8 induced strong innate immune responses and enhanced resistance to the oomycete pathogen Phytophthora capsici in Solanaceae plants, including Nicotiana benthamiana , tomato, and pepper. Cell death and reactive oxygen species (ROS) accumulation triggered by the PoEli8 protein were dependent on the plant coreceptors receptor-like kinases (RLKs) BAK1 and SOBIR1. Furthermore, REli from N. benthamiana , a cell surface receptor-like protein (RLP) was implicated in the perception of PoEli8 in N. benthamiana . These results indicate the potential value of PoEli8 as a bioactive formula to protect Solanaceae plants against Phytophthora .