CsCOI1 regulates plant growth and defense in citrus

Jasmonates (JAs) play essential roles in plant development and defense. JA perception and responses remain elusive in citrus. Here, we identified core components for JA perception in citrus and elucidated transcriptional changes associated with JA signaling in growth and defense. We showed the F-box protein CORONATINE INSENSITIVE1 (COI1) in citrus is a JA receptor, as CsCOI1 mutants are insensitive to methyl jasmonate and CsCOI1 interacts with CsJAZs in the presence of JA-Ile. CsCOI1-mediated JA signaling represses shoot growth while enhancing resistance to insects. Consistently, CsCOI1 represses the expression of growth promoting genes such as PIF7, while upregulating genes related to defense metabolites in terpene and flavonoid pathways. Additionally, JA signaling antagonizes salicylic acid (SA) signaling at the transcriptional level and promotes susceptibility to citrus canker disease. This study highlights the role of JA signaling in balancing growth and resistance to biotic stress in citrus, revealing critical trade-offs for consideration in precision citrus breeding.