γ-Aminobutyric Acid (GABA) enhances heat tolerance in rice via integrated antioxidant defense, metabolic homeostasis and heat shock response.

BACKGROUND

Global warming has increased the frequency and intensity of extreme heat events, posing a serious threat to crop growth and productivity. Although γ‑aminobutyric acid (GABA) is recognized as a bioactive factor functioning in plant stress adaptation, its specific role and underlying mechanisms under heat stress remain poorly understood in rice.

RESULTS

In this study, we demonstrate that exogenous GABA significantly enhances heat tolerance in rice seedlings in a dose‑dependent manner. Application of 0.1 mM GABA effectively alleviated heat-induced growth inhibition and mitigated oxidative damage by suppressing reactive oxygen species (ROS) accumulation, membrane lipid peroxidation, and cell death. This protection was associated with enhanced antioxidant capacity, evidenced by up‑regulation of key antioxidant enzymes and elevated glutathione levels. Moreover, transcriptome and quantitative analysis revealed that GABA supplementation finely reconfigures the heat‑induced accumulation of specific amino acids and carbohydrates, thereby promoting metabolic homeostasis under heat stress. We further show that GABA modulates heat signaling pathway and amplifies the heat-induced expression of heat shock transcription factors (HSFs), which in turn drives stronger induction of downstream heat‑responsive genes, such as heat shock protein (HSP) and antioxidant enzyme genes.

CONCLUSION

Together, these findings indicate that GABA coordinates multiple adaptive mechanisms, including enhancing antioxidant capacity, optimizing metabolic homeostasis, and activating heat‑responsive transcription, thereby enhancing rice heat tolerance. Our study highlights GABA as a promising biostimulant for improving heat resilience in crops and provides a viable strategy for sustainable crop production under climate warming.