PlMYB34-PlABI5 synergistically regulate Paeonia lactiflora seed dormancy via ABA metabolism and signaling pathways

Paeonia lactiflora Pall. is a valuable ornamental and medicinal plant, but its strong seed dormancy limits breeding efficiency. Abscisic acid (ABA) plays a central role in regulating seed dormancy, yet its mechanism in P. lactiflora remains poorly understood. In this study, we identified PlABI5, a core transcription factor in the ABA signaling pathway, and its interacting protein PlMYB34 as key regulators of seed dormancy. Exogenous ABA treatment induced the expression of PlABI5 and PlMYB34, and their overexpression significantly enhanced dormancy in P. lactiflora. Together, PlABI5 and PlMYB34 regulated the expression of protein phosphatase gene PlPP2C24 and the ABA-biosynthesis gene PlNCED2, thereby promoting ABA accumulation and increasing seed sensitivity to ABA. This positive feedback strengthened dormancy control. Our findings demonstrate that PlABI5 and PlMYB34 fine-tuned seed dormancy in P. lactiflora by integrating ABA signaling and biosynthesis pathways, broadening our understanding of seed-dormancy mechanisms in plants and providing targets for overcoming dormancy to accelerate P. lactiflora breeding.