Lapachol, a naphthoquinone identified through chemical screening, inhibits plant immunity

Quinones, a ubiquitous class of organic compounds produced in all kingdoms of life, are recognized for their diverse biological functions. In plants, quinones are implicated in allelopathy, where they act as allelochemicals influencing the growth and development of neighboring plants, of which one well-documented role of quinone is in the induction of haustoria of parasitic plant roots. In this study, through an immune marker gene-based chemical biology screening, we identified Lapachol, a naphthoquinone originally isolated from species of the Bignoniaceae family. Lapachol suppresses elicitor-triggered typical innate immunity responses, such as calcium influx, ROS burst, MAPK activation and defense-related gene expressions. Structure-activity-relationship studies revealed that various quinones could inhibit the hallmarks of plant immune responses but not the redox-related compounds and other haustoria-inducing factors. In addition, the pretreatment of quinone molecules inhibited flg22-induced plant resistance to Botrytis cinerea. Collectively, our discovery elucidates the novel function of quinones underpinnings of quinone-mediated plant-plant and plant-pathogen interactions, providing insights into the plant-organism interactions mediated by these natural products.