The TaCOMT1A-Synthesised Sakuranetin Is a Novel Biostimulant Enhancing Drought Tolerance and Yield in Wheat

Drought stress is a major limitation to global wheat production. Here, we demonstrate that the wheat gene TaCOMT1A, encoding a caffeic acid O-methyltransferase, plays a crucial role in enhancing drought tolerance in wheat. Overexpression of TaCOMT1A significantly improved drought tolerance at the seedling stage, as evidenced by higher survival rates, biomass, and antioxidant capacity, along with reduced oxidative damage in transgenic lines. Field trials demonstrated that these lines maintained superior grain yield under limited irrigation. We identified TaCOMT1A as a multifunctional enzyme capable of synthesising both the flavonoid sakuranetin and melatonin in vitro. Metabolomic and functional analyses confirmed that sakuranetin is a key downstream metabolite mediating the drought tolerance conferred by TaCOMT1A. Exogenous application of sakuranetin enhanced drought tolerance across diverse wheat cultivars and, importantly, rescued the susceptible phenotype of TaCOMT1A EMS mutants (E829 and E830). Mechanistically, sakuranetin treatment bolstered the antioxidant system and attenuated oxidative stress under drought. Furthermore, both TaCOMT1A overexpression and sakuranetin application reduced plant height by suppressing gibberellic acid (GA₃) biosynthesis. Crucially, field application of sakuranetin increased grain yield under both well-irrigated and drought conditions. Our results establish a novel pathway where TaCOMT1A enhances drought tolerance and modulates plant architecture primarily through the production of sakuranetin, positioning this metabolite as a promising plant-based priming agent for sustainable wheat cultivation.