Blocking the isoflavone chemoreceptor in <i>Phytophthora sojae</i> to prevent disease

Abstract

Inhibiting pathogen chemotaxis is a promising strategy for reducing disease pressure. However, this strategy is currently in the proof-of-concept stage. Here, <i>Phytophthora sojae</i> was used as a model, as its biflagellated zoospores could sense genistein, a soybean root exudate, to navigate host and initiate infection. We identify <i>P. sojae</i> IRK1 (isoflavone-insensitive receptor kinase 1) as a receptor for genistein, with PsIRK2 functioning as a coreceptor that enhances the binding affinity of PsIRK1 to genistein and regulates chemotaxis by phosphorylating G protein α subunit. Last, we identify an antagonist, esculetin, which disrupts the PsIRK1-genistein interaction, thereby preventing <i>P. sojae</i> infection by repelling zoospores. Our findings reveal the mechanism by which <i>P. sojae</i> senses host genistein and demonstrate a strategy for disease prevention by targeting the chemoreceptor.