Modulation of Enhanced Antioxidant Activity by Hydrogen Sulfide Antagonization of Ethylene in Tomato Fruit Ripening.

Ethylene (CH) and hydrogen sulfide (HS) play important physiological roles in regulating fruit ripening and senescence. The mechanism of HS in ethylene-induced tomato fruit ripening and senescence is still unknown. Here, we show that exogenous HS reduced the production of superoxide anion (·O), malondialdehyde (MDA), and HO in tomato fruit. Further, additional HS was found to induce the activities of guaiacol peroxidase, catalase, ascorbate peroxidase, and superoxide dismutase compared with CH treatment alone, whereas the activities of lipoxygenase, polyphenol oxidase, and phenylalanine ammonia lyase were adversely affected. Moreover, the expression of the antioxidant-encoding genes SlAPX2, SlCAT1, SlPOD12, and SlCuZnSOD was generally up-regulated with CH-HS cotreatment, compared with their expression after ethylene treatment. Thus, the present results suggest that exogenous HS acts as a fruit-ripening regulator by antagonizing the effect of ethylene, thereby providing a potential application for HS in the postharvest storage of fruit.