PpAP2-like as a positive regulator participates ALA-induced SPS to promote sucrose accumulation in early-maturing...

Sucrose phosphate synthase (SPS) is pivotal for sucrose biosynthesis in peach fruit, yet its regulatory mechanisms underlying 5-aminolevulinic acid (ALA)-mediated sucrose accumulation remain unclear. This study revealed that exogenous ALA significantly enhances sucrose content and SPS activity in early-ripening peach (Prunus persica 'Zaoxing No.2'). Yeast one-hybrid (Y1H) screening identified PpAP2-like, an AP2/ERF transcription factor, which exhibited nuclear localization, transcriptional activation activity. The result of Y1H showed that PpAP2-like interacted with the promoter of PpSPS2. ALA positively regulates PpAP2-like to promote PpSPS2 expression. Dual-luciferase and GUS reporter systems confirmed that ALA positively regulates PpAP2-like to promote PpSPS2 expression. Furthermore, ALA treatment upregulated PpAP2-like expression, which correlated positively with SPS activity and sucrose accumulation during fruit development. These findings elucidate a molecular pathway whereby ALA promotes sucrose biosynthesis via PpAP2-like-mediated transcriptional regulation of PpSPS2, providing critical insights for optimizing fruit quality and advancing molecular breeding strategies in peach.