Hydrogen sulfide alleviates postharvest ripening and senescence of banana by antagonizing the effect of ethylene

Accumulating evidence shows that hydrogen sulfide (H(2)S) acts as a multifunctional signaling molecule in plants, whereas the interaction between H(2)S and ethylene is still unclear. In the present study we investigated the role of H(2)S in ethylene-promoted banana ripening and senescence by the application of ethylene released from 1.0 g·L(−1) ethephon solution or H(2)S with 1 mM sodium hydrosulfide (NaHS) as the donor or in combination. Fumigation with ethylene was found to accelerate banana ripening and H(2)S treatment effectively alleviated ethylene-induced banana peel yellowing and fruit softening in parallel with decreased activity of polygalacturonase (PG). Ethylene+H(2)S treatment also delayed the decreases in chlorophyll and total phenolics, and increased the accumulation of flavonoid, whereas decreased the contents of carotenoid, soluble protein in banana peel and reducing sugar in pulp compared with ethylene treatment alone. Besides, ethylene+H(2)S treatment suppressed the accumulation of superoxide radicals (·O(2)(−)), hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) which accumulated highly in ethylene-treated banana peels. Furthermore H(2)S enhanced total antioxidant capacity in ethylene-treated banana peels with the 2,2’-azobis(3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) assay. The result of quantitative real-time PCR showed that the combined treatment of ethylene with H(2)S down-regulated the expression of ethylene synthesis genes MaACS1, MaACS2 and MaACO1 and pectate lyase MaPL compared with ethylene treatment, while the expression of ethylene receptor genes MaETR, MaERS1 and MaERS2 was enhanced in combination treatment compared with ethylene alone. In all, it can be concluded that H(2)S alleviates banana fruit ripening and senescence by antagonizing the effect of ethylene through reduction of oxidative stress and inhibition of ethylene signaling pathway.