WLG coordinates multi-stress tolerance in rice by regulating DST-dependent H2O2 homeostasis and stomatal aperture.

Abiotic stresses reduce rice growth and yield, yet the mechanisms underlying multiple stress tolerance are unknown. Here, we show that the E3 ubiquitin ligase WIDTH OF LEAF AND GRAIN (WLG) enhances drought, salt, and heat tolerance by ubiquitinating and degrading DROUGHT AND SALT TOLERANCE (DST). This degradation represses PEROXIDASE 24 PRECURSOR (Prx24) expression, increasing guard-cell H2O2 accumulation, reducing stomatal conductance and transpiration rate, thereby improving water retention and limiting sodium uptake under abiotic stress conditions. Elevated H2O2 also induces the expression of heat shock proteins, contributing to enhanced tolerance to heat stress. DST, in turn, transcriptionally represses WLG, establishing a negative feedback loop that fine-tunes H2O2 homeostasis and stress responses. Moreover, WLGhap.B promotes stronger DST degradation than WLGhap.A. Our findings elucidated the WLG-DST-Prx24 module as a central regulatory mechanism governing H2O2 dynamics under multiple abiotic stresses, highlighting the potential of WLGhap.B for developing multiple stress-resistant rice varieties in a changing climate.