Cross-species expression of OsDJ-1C from rice enhances tolerance to salinity and drought stress in tomato

Abstract

Abiotic stresses such as salinity and drought induce the accumulation of methylglyoxal (MG), a highly cytotoxic dicarbonyl compound that disrupts cellular metabolism in plants. MG detoxification is primarily mediated by the glutathione-dependent glyoxalase pathway, classically comprising the enzymes glyoxalase I and II. In contrast, glyoxalase III (GLYIII) catalyzes detoxification of MG in a single-step without requiring glutathione. In the present study, we investigated the functional role of OsDJ-1C, a rice GLYIII enzyme, by heterologous overexpression in tomato (Solanum lycopersicum). Transgenic lines exhibited significantly enhanced stress tolerance through a more efficient antioxidant defense mechanism under stress conditions. This improvement was driven by increased GLYIII-mediated detoxification of MG, leading to effective suppression of reactive oxygen species (ROS) accumulation. Reduced ROS levels in the overexpression lines resulted in greater internal oxygen availability and enhanced cellular respiration than wild-type plants. Furthermore, transgenic plants maintained higher pyruvate levels than the wild-type controls, thereby sustaining tricarboxylic acid (TCA) cycle flux and ATP production under stress. Overall, these findings reveal a conserved, cross-species function of OsDJ-1C in enhancing abiotic stress tolerance emphasizing its relevance for improving agricultural sustainability and food security under changing climatic conditions.