The PuWRKY29-PuMYB62 module responds to salicylic acid to inhibit the synthesis of stone cells in 'Nanguo' pear.

Stone cells serve as pivotal determinants of pear fruit quality, with their formation exhibiting a strong correlation with lignification processes. As a phenolic signaling molecule with multiple biological functions, salicylic acid (SA) plays essential roles in regulating fruit growth and developmental processes. Nevertheless, the molecular mechanisms underlying SA-mediated modulation of stone cell differentiation in pears remain poorly characterized. Our investigation revealed that exogenous application of 15 mg L SA decreased lignified stone cell formation in 'Nanguo' (Pyrus ussuriensis) pear fruits and significantly downregulating the expression of the lignin biosynthesis-related PuPRX64. mRNA-seq identified two transcription factors, PuWRKY29 and PuMYB62, which were significantly induced by SA. Functional characterization through transient expression assays in pear fruits and stable transgenic calli demonstrated that both factors act as negative regulators of stone cell formation and lignin accumulation. PuWRKY29 binds to the W-box cis-element within the PuMYB62 promoter to activate its transcription, while simultaneously forming a protein complex that synergistically represses PuPRX64 expression. Collectively, our findings suggest that exogenous SA treatment inhibits stone cell and lignin biosynthesis in pears via the PuWRKY29-PuMYB62 regulatory module.