Boosting Drought Resilience in Rice: The Priming Effects of Zaxinone and Its Mimics

Climate change increasingly threatens global agriculture, with drought emerging as a major constraint on crop productivity. Plants activate complex adaptive responses, involving genetic, physiological, and hormonal networks, to cope with water deficit. Among these, carotenoid-derived phytohormones, abscisic acid, and strigolactones regulate drought responses through mod- ulation of stomatal conductance, antioxidant defenses, and hormonal crosstalk. Zaxinone, an apocarotenoid metabolite, and its synthetic analogs Mimic of Zaxinone 3 (MiZax3) and MiZax5 have recently emerged as plant growth regulators and SL biosynthesis inhibitors in Oryza sativa. This study investigates the effects of zaxinone and its mimics on rice drought encom- passing morphometric, ecophysiological, biochemical, and molecular analysis. Exogenous treatment prior to the water deficit revealed compound-specific effects, in an organ-specific manner, on stomatal conductance, transpiration rate, and stem water potential. We also observed differential ABA and zaxinone content and transcriptional regulation of stress-related genes across water regimes. Notably, MiZax5 treatment maintained higher Ψstem and modulated stress-responsive gene expression at the end of drought, suggesting improved osmotic adjustments and enhanced stress resilience. Our results highlight the potential of zaxinone-based compounds as promising biostimulants capable of priming rice for improved drought resilience, offering a sus- tainable approach to boost crop performance under abiotic stress