P-354 - BIN2-mediated ORA59 phosphorylation promotes disease resistance against Botrytis cinerea in Arabidopsis

Ethylene (ET) and jasmonic acid (JA) are essential for plant defense against necrotic pathogens, acting by modulating gene expression via transcription factors. The transcription factor ORA59, which preferentially binds to ERLEE4 and the GCC box, plays a crucial role in this process. We demonstrate that ORA59 interacts with brassinosteroid insensitive2 (BIN2), a negative regulator of the brassinosteroid signaling pathway. BIN2 phosphorylates three serine residues on ORA59, impacting its stability and transcriptional activity. Notably, this modulation is selectively enhanced by the JA signaling pathway, influencing ORA59's binding preference for the GCC box. Furthermore, BIN2 activity is regulated by the JA pathway through COI1-dependent control of its negative regulators. Our findings highlight BIN2 as a crucial regulator of ORA59, significantly contributing to the complex network of plant defense mechanisms.