Research Progress on Chitosan Enhancing Plant Stress Resistance

As a natural and safe plant immunity elicitor, chitosan can systematically regulate the stress-resistant physiological network of plants. This review systematically summarizes the research progress on chitosan in the field of plant stress resistance, aiming to provide a theoretical reference for its further development and application in agricultural production. In terms of biotic stress, chitosan mimics pathogen-associated molecular patterns, is recognized by plant pattern recognition receptors, thereby initiating early defense signals and exhibiting broad-spectrum resistance against fungal, bacterial, and viral diseases. In terms of abiotic stress, chitosan enhances plant tolerance through multi-pathway synergistic effects: under drought conditions, it improves drought resistance by optimizing water management and enhancing antioxidant capacity; under low-temperature stress, it enhances cold resistance by inducing the expression of cold-responsive genes and stabilizing the photosynthetic apparatus; in saline-alkali environments, it improves salt tolerance by regulating ion homeostasis and maintaining photosynthetic performance; under heavy metal contamination, it reduces bioavailability and toxicity through functional group chelation and inhibition of metal transport. Future research should focus on the in-depth dissection of molecular mechanisms, the directed development of functionalized derivatives, and the establishment of field application technology systems. These efforts are essential to promote the transition of chitosan from basic research to large-scale and precise application in green agricultural production.