Cross-tolerance and Stress Memory in Rice: Evaluating Drought-tolerant Genotypes for Salinity Tolerance and Priming Effects

Abstract

Rice, the staple food for over half the world’s population, is highly susceptible to salinity and drought stresses that often coincide and elicit overlapping physiological responses. This study explored stress memory and cross-tolerance mechanisms in four rice genotypes subjected to a single reproductive-stage salinity stress (T3) or repeated vegetative-reproductive stresses (T4). While T3 plants exhibited superior morphological traits, T4 plants showed enhanced biochemical preparedness, including higher protein, peroxidase, proline, and flavonoid content. Despite reduced vegetative vigour, T4 plants yielded slightly higher grain, indicating that stress memory-driven physiological acclimation enhances reproductive tolerance. Drought-tolerant genotypes Dhaksha and GEN_214 consistently outperformed susceptible genotypes, showing strong osmolyte accumulation, antioxidant activity, and water retention. However, both stress regimes caused significant (>82%) yield loss, confirming that reproductive stages remain highly vulnerable. The findings revealed that shared osmolyte and antioxidant responses mediate cross-tolerance between drought and salinity, highlighting salinity screening as a valuable surrogate approach for developing drought-resilient rice cultivars under climate stress.