The MYC2-PUB22-JAZ4 module plays a crucial role in jasmonate signaling in tomato

Jasmonates (JAs), a class of lipid-derived stress hormones, play a crucial role across an array of plant physiological processes and stress responses. While JA signaling is generally thought to rely dominantly on the degradation of specific JASMONATE-ZIM DOMAIN (JAZ) proteins by SCFCOI1, it remains unclear whether other pathways are involved in the regulation of JAZ protein stability. Here, we report that PUB22, a plant U-box type E3 ubiquitin ligase, plays a vital role in the regulation of the resistance against Helicoverpa armigera and other JA responses in tomato. While COI1 physically interacts with JAZ1/2/5/7, PUB22 physically interacts with JAZ1/3/4/6. PUB22 ubiquitinates JAZ4 to promote its degradation via 26S proteasome pathway. Importantly, pub22 mutants had decreased whilst jaz4 mutants and jaz1 jaz3 jaz4 jaz6 quadruple mutants had enhanced resistance against H. armigera. The hypersensitivity to herbivores for pub22 mutants was partially rescued by JAZ4 mutation. Moreover, PUB22 expression was transcriptionally activated by MYC2, thus forming a positive feedback circuit in JA signaling. Notably, the PUB22-JAZ4 module regulated various JA responses, including the defense against Botrytis cinerea, root elongation inhibition and anthocyanin accumulation. Taken together, PUB22 plays a crucial role in plant response to environmental changes in concert with the COI1-regulated JA signaling by targeting specific JAZs.