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

Ethylene (C2 H4 ) and hydrogen sulfide (H2 S) play important physiological roles in regulating fruit ripening and senescence. The mechanism of H2 S in ethylene-induced tomato fruit ripening and senescence is still unknown. Here, we show that exogenous H2 S reduced the production of superoxide anion (·O2 - ), malondialdehyde (MDA), and H2 O2 in tomato fruit. Further, additional H2 S was found to induce the activities of guaiacol peroxidase, catalase, ascorbate peroxidase, and superoxide dismutase compared with C2 H4 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 C2 H4 -H2 S cotreatment, compared with their expression after ethylene treatment. Thus, the present results suggest that exogenous H2 S acts as a fruit-ripening regulator by antagonizing the effect of ethylene, thereby providing a potential application for H2 S in the postharvest storage of fruit.