Abstract: In this study, the effect of preharvest chitosan (CTS) foliar application on the field growth and disease resistance of potato plants as well as the post-harvest storage characteristics of tubers (cv. ‘Longshu 7’) was investigated. Proteomic analysis was conducted to identify differentially expressed proteins and potential metabolic pathways during the development of dry rot in potato tubers after challenge inoculation with Fusarium sambucinum. Furthermore, physiological analyses were carried out to elucidate the possible mechanism by which pre-harvest CTS treatment induces resistance to dry rot in potato tubers. The results showed that pre-harvest CTS treatment promoted the increase of plant height and stem diameter in potato, reduced the field late blight disease index, maintained lower respiration rate, mass loss rate, natural incidence rate, and decay index of tubers during storage, and improved post-harvest disease resistance and storage performance. Proteomic results indicated that after challenge inoculation with F. sambucinum, the glutathione (GSH) metabolic pathway was activated in the CTS-treated group compared with the control group. Physiological results showed that pre-harvest CTS treatment significantly enhanced the activity and gene expression of superoxide dismutase (SOD), increased the gene expression and activity of key enzymes as well as metabolite contents in the GSH pathway, significantly reduced the accumulation of reactive oxygen species (superoxide anion radical and H2O2), but did not change significantly the activity and gene expression of catalase (CAT) in the early stage of disease development. The CTS-treated group significantly inhibited the increase of malondialdehyde (MDA) and cell membrane permeability. In summary, pre-harvest CTS treatment enhances the post-harvest antioxidant capacity of potato tubers by activating GSH metabolism. This mitigates oxidative damage, suppresses the expansion of dry rot lesions, and ultimately enhances resistance to F. sambucinum. This study’s findings offer a new strategy for the green control of this disease.

Key words: potato; chitosan; oxidative stress; glutathione metabolism