Abstract: In order to understand the e?ect of chitosan treatment on the postharvest disease development of Passiflora caerulea L. and the underlying mechanisms, freshly harvested fruit (cv. Fujian Baixiangguo 1) were soaked in distilled water (control) and a 1:200 dilution of Kadozan (a novel chitosan formulation) for 5 min, separately, and then stored at (28 ± 1) ℃. Disease index, disease resistance-related enzyme activities and disease resistance-related substance contents were measured every three days. The results indicated that chitosan treatment could significantly reduce disease index of Passiflora caerulea L. fruit during postharvest storage (P < 0.05, P < 0.01); on day 15, the disease index of the treated fruit was 2.21, which was only 55.39% of that (3.99) of the control fruit. In addition, compared with the control fruit, chitosan treated-fruit maintained higher contents of total phenols and lignin, and higher activities of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), polyphenol oxidase (PPO), peroxidase (POD), chitinase (CHI), and β-1,3-glucanase (GLU) in the pericarp. These findings suggested that chitosan treatment could enhance disease resistance of harvested Passiflora caerulea L. fruit, consequently suppress the development of postharvest diseases and prolong the storage life by promoting the generation and accumulation of disease resistance-related substances and increase the activities of disease defense-related enzymes in the pericarp.

Key words: Passiflora caerulea L. fruit; postharvest disease; disease resistance-related substances; disease resistance-related enzymes; chitosan