Abstract: Jasmonic acid (JA) is a critical signal controlling ripening and trait development in non-climacteric (NC) fruit. However, the mechanisms governing the JA biosynthesis remain unclear. Here, the signaling mechanisms for the JA biosynthesis are explored in strawberry (Fragaria vesca), a model NC fruit. The JA biosynthesis is demonstrated to be tightly coupled with the signaling of ABA, a pivotal signal controlling NC fruit ripening. When overexpressed or knocked out by CRISPR/Cas9 editing, FvSnRK2.6, a gene encoding a component of ABA signaling, promotes or inhibits JA production and aroma production, respectively. Moreover, FvSnRK2.6 phosphorylates FvJAZ12, a jasmonate ZIM-domain repressor, at the S142 residue, thereby promoting its degradation. Transforming the FvJAZ12 knockout mutant with FvJAZ12^S142A inhibits the production of ABA-induced aroma and JA. Furthermore, our current study reveals that FvMYC2, a transcription factor directly repressed by FvJAZ12, binds to cis-acting elements in the promoters of FvAOC3, FvAOS, FvLOX3, and FvOPR3, thus directly regulating JA biosynthesis. Thus, this study reveals an ABA signaling cascade that leads to JA biosynthesis, thereby elucidating the signaling mechanism governing the JA production during strawberry fruit ripening.

Key words: abscisic acid, aroma formation, fruit ripening, jasmonic acid, signaling cascade, strawberry