Hydrogen sulfide enhances the disease resistance of ginger to rhizome rot during postharvest storage through modulation of antioxidant response and nitric oxide-mediated S-nitrosylaion

Abstract

Postharvest pathogenic infestation leads to the quality deterioration in ginger industry. Hydrogen sulfide (H₂S), as an emerging potential postharvest protectant, could enhance disease resistance. This study investigated the antifungal role of H₂S against Fusarium solani during ginger postharvest storage. The results showed that H₂S restricted widespread infection by F. solani in gingers and have direct antimicrobial activity against F. solani in vitro, inhibiting mycelial growth and spore germination. H₂S improved endogenous H₂S accumulation, increased the activities of POD, CAT and SOD, and facilitated the removal of excess ROS. It also promoted the lignin, total phenolic and flavonoid contents, while boosting the activities of PAL, C4H and 4CL, and up-regulating the expression of ZoPAL, ZoC4H and Zo4CL. Moreover, H₂S increased endogenous NO levels through the NR and NOS pathways. Notably, the endogenous SNO content was increased, the GSNOR activity as well as expression of GSNOR were down-regulated by H₂S treatment. These effects were reversed by hypotaurine (HT), a scavenger of H₂S. Together, these results indicated that H₂S induces the disease resistance in postharvest ginger storage via enhancing antioxidant and defense capacity, regulating phenylpropane metabolism, inducing NO production and mediating NO-dependent S-nitrosylation modification. These results provide guidance for the application of H₂S during the storage of ginger.