Cadmium-drought interaction modulates oxidative stress, antioxidant defense, and stress-responsive gene in rice...

Concurrent exposure to cadmium (Cd) and drought stress induces significant physiological and biochemical alterations in plants. As a heavy metal accumulator, rice poses a potential health risk when consumed. The intricate molecular and physiological mechanisms underlying the effects of multiple abiotic stresses on rice sprouts remain poorly understood. In this study, Cd/drought-tolerant rice cv. Anjali and Cd/drought-sensitive rice cv. HUR-105 plants were exposed to 100 µM Cd alone, 15% PEG-6000 alone induced drought stress, and 100 µM Cd + 15% PEG-6000 in combination form. ROS formation and membrane damage were investigated by confocal analysis, leaf ultrastructure by SEM analysis, and photosynthetic pigments and antioxidant enzyme activities by biochemical analysis. RNA isolation, cDNA synthesis, and gene expression analysis were conducted to examine the modulation of gene expression in response to Cd and/or drought stress, including OsHMA2, OsNramp5, OsMn-SOD, OsCu-Zn SOD, OsGPx 01, OsGPx02, and OsDREB2A. Results demonstrate differential responses between the two cultivars, cv. Anjali exhibited significantly higher transcript levels of key stress-responsive genes such as OsMn-SOD, OsCu-Zn SOD, OsGPx 01, OsGPx 02, and OsDREB2A than cv. HUR-105 under Cd-and/or-PEG-6000 treatments. Multivariate analyses (PCA and hierarchical clustering heatmap) of physiological and biochemical traits further confirmed the presence of clear treatment-specific patterns and high reproducibility, supporting the observed physiological and molecular differences. In conclusion, the study bridges our understanding of plant stress responses and underscores the importance of considering interactive stressors in agricultural management practices.

The online version contains supplementary material available at 10.1007/s12298-026-01709-3.