Phosphate starvation primes plant immunity through an ABA–OsbZIP12–phytoalexin signaling network

Phosphate (Pi) starvation is a major constraint on crop productivity, yet its effects on disease resistance remain poorly understood. Abscisic acid (ABA) is central to abiotic stress responses, but its interactions with nutritional cues and immunity remain unclear. Here, we reveal how Pi starvation enhances rice blast resistance through an ABA-mediated signaling network. We found that Pi-starved rice exhibits elevated ABA, increased accumulation of the phytoalexin sakuranetin (SAK), and enhanced resistance to Magnaporthe oryzae. Strikingly, ABA exerts a biphasic effect on immunity: brief exposure to high ABA concentrations suppresses resistance, whereas sustained treatment with low concentrations promotes it by differentially regulating SAK biosynthesis and endogenous ABA homeostasis. We identified the transcription factor OsbZIP12 as a key integrator of these signals. OsbZIP12 directly activates the SAK biosynthesis gene OsNOMT and is itself regulated by Pi starvation and through ABA signaling. Genetic analyses confirmed that OsbZIP12 is essential for this SAK-dependent resistance. Our findings define a Pi-ABA-immunity network coordinated by OsbZIP12 and identify potential molecular targets for leveraging nutritional stress to enhance crop resilience.