Oxidative Stress in Lactuca sativa L.: Cellular Mechanisms, Stress Responses, and Mitigation Strategies

Lettuce is a vegetable crop of major importance in the global diet due to its low caloric content and high levels of fiber, minerals, vitamins, and antioxidant compounds. China is the world's leading lettuce producer, accounting for more than 50% of global production. However, climate change and anthropogenic activities expose agricultural crops to both biotic and abiotic stresses, including drought, salinity, and heavy metal contamination. These adverse conditions induce the overproduction of reactive oxygen species, resulting in redox imbalance that damages lipids, proteins, and nucleic acids, ultimately leading to wilting, chlorosis, necrosis, and reductions in plant growth and nutritional value. To counteract cellular damage, this review describes various strategies for mitigating oxidative stress in lettuce crops. These approaches include the exogenous application of antioxidants and osmoprotectants, the use of biostimulants, nanopriming techniques, nanoparticles, encapsulated delivery systems, genome editing, and genetic engineering. Finally, this review concludes that oxidative stress management should evolve toward an integrated, precision-based approach combining two or more complementary strategies to ensure crop sustainability, commercial yield, and food security under challenging environmental conditions.