Abstract: This study aimed to investigate the effect of arginine treatment on the occurrence of postharvest gray mold in ‘Zhongshu No. 4’ tomato fruit and the role and mechanism of nitric oxide synthase (NOS) pathway in arginine-induced disease resistance during storage at (25 ± 1) ℃. The results indicated that 5.0 mmol/L arginine was the most effective treatment in reducing the incidence of gray mold and lesion area in tomato fruit in the concentration range of 0.0–10.0 mmol/L. Moreover, 5.0 mmol/L arginine treatment increased NOS activity and nitric oxide (NO) content. Total phenol content and the activities of phenylalanine ammonia-lyase, polyphenol oxidase, chitinase and β-1,3-glucanase were also enhanced remarkably. Besides, the expression of pathogenesis-related genes (PR2a, PR2b, PR3a and PR3b) were induced significantly. However, these effects were partially counteracted by Nω-nitro-L-arginine, an inhibitor of NOS. Our results indicate that arginine-induced resistance to gray mold in postharvest tomato fruit may be due to promoting the NOS pathway.

Key words: tomato fruit, nitric oxide synthase, arginine, disease resistance