Exogenous application of hydrogen sulfide combined with blue light improves the quality of pepper fruit minimizing oxidative stress during postharvest storage.

While the roles of hydrogen sulfide (H2S) as a source of supersulfide and blue light (BL) in overall plant growth are established, their precise involvement in fruit ripening is still obscured. We focused on the specific roles of the combination of those (H2S + BL) treatments that might delay the ripening of pepper fruit for better postharvest storage. In this experiment, harvested fruits were treated with H2S from 1 mM sodium hydrogen sulfide (NaHS) solution following storage under BL (470 nm at 40 μmol m-2 s-1) for 7 days at 25 °C. The results demonstrated that H2S + BL regulated decay rate, weight loss, firmness of fruit coat, and respiratory rate. The treatment was found effective in the regulation of anthocyanin, photochemical and thermal quenching. Fruits maintained postharvest photosynthesis under H2S + BL through malic acid metabolism by NADP-ME malic enzyme. The treatment significantly induced biosynthesis of H2S, and cysteine by upregulating L-cysteine desulfhydrase and D-cysteine desulfhydrase activities. Oxidative injuries during ripening were reduced by H2S + BL treatment, which lowered hydrogen peroxide and malondialdehyde levels and decreased ion leakage. Increased concentration of glutathione directly substantiated with gene expression for superoxide dismutase and catalase. A significant variation in phenolic compounds was detected from fruits under storage with a positive correlation with sulfur content. Finally, the delayed ripening under H2S + BL was corroborated with higher cell viability and minimized loss of DNA. Conclusively, combining H2S and BL proves efficient for delayed pepper fruit senescence, potentially contributing sustainably to maintaining postharvest quality.