Control of Alternaria alternata by sodium alginate and natamycin treatments of sweet cherry

Natamycin, a natural antifungal produced through fermentation by streptomyces, can promote postharvest disease resistance in fruit. Sodium alginate is often used as film-forming matrices for fabricating antibacterial composite coatings for the preservation of fruit and vegetables. This study investigated the inhibitory effects of sodium alginate, natamycin, or combined treatment on Alternaria alternata infection in 'Jimei' sweet cherry postharvest using various biochemical and enzyme assays along with spectrophotometry. The results showed that the combined treatment of natamycin and sodium alginate inhibited the development of A. alternata . After 7 d of treatment, the lesion diameter of the combined treatment fruit was 64.4 % lower than that of the control. Further studies showed that the combined treatment significantly reduced the contents of hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 - ·) and malondialdehyde (MDA) in the fruit defense system, and enhanced the activities of antioxidant enzymes, chitinase (CHI) and β-1,3-glucanase (GLU). The results showed that the combined treatment of postharvest natamycin and sodium alginate effectively enhanced disease resistance by inhibiting the production of reactive oxygen species (ROS) and activating defense-related proteins in cherry fruits. • Sodium alginate and natamycin treatment (SN) ameliorated antioxidant capacity. • SN treatment efficiently inhibited mycelial growth of Alternaria alternata in vitro. • SN treatment increases the accumulation of host pathogenesis-related protein. • SN treatment activated phenylpropanoid pathway involved in the disease resistance.