Subtype-selective agonists of plant hormone co-receptor COI1-JAZs identified from the stereoisomers of coronatine.

Severe genetic redundancy is particularly clear in gene families encoding plant hormone receptors, each subtype sharing redundant and specific functions. Genetic redundancy of receptor family members represents a major challenge for the functional dissection of each receptor subtype. A paradigmatic example is the perception of the hormone (+)-7-iso-jasmonoyl-L-isoleucine, perceived by several COI1-JAZ complexes; the specific role of each receptor subtype still remains elusive. Subtype-selective agonists of the receptor are valuable tools for analyzing the responses regulated by individual receptor subtypes. We constructed a stereoisomer library consisting of all stereochemical isomers of coronatine (COR), a mimic of the plant hormone (+)-7-iso-jasmonoyl-L-isoleucine, to identify subtype-selective agonists for COI1-JAZ co-receptors in Arabidopsis thaliana and Solanum lycopersicum. An agonist selective for the Arabidopsis COI1-JAZ9 co-receptor efficiently revealed that JAZ9 is not involved in most of the gene downregulation caused by COR, and the degradation of JAZ9-induced defense without inhibiting growth.