ZnCl2 inhibits postharvest disease on pear and crabapple by inducing autophagy of Penicillium expansum.

Penicillium expansum is a phytopathogen causing postharvest disease of many fruits, which has led to enormous losses. Therefore, it is of great significance to take efficient methods to control this notorious phytopathogen. In this study, zinc, an essential trace element for human body, has been found to be able to effectively inhibit the P. expansum mycelial growth on PDA and burst of ROS in the fungal hyphae. Additionally, the transmission electron microscope (TEM) analysis indicated that zinc induces autophagy and autophagic vacuoles in P. expansum. Furthermore, the zinc inhibits the activity of six key enzymes (PDH, SDH, CS, IDH, MDH, KGDH) in TCA pathway to inhibit the growth of P. expansum. The decrease of ATPase activity indicated that the function of mitochondria in P. expansum was destroyed after the treatment of zinc. Finally, the sodium alginate (SA)@ZnCl2 coatings were verified to be effective in inhibiting the postharvest disease of pear and crabapple. Collectively, all the above results showed that zinc had great efficacy in suppressing P. expansum on fruit surfaces by inducing autophagy.