Hydrogen sulfide reduces postharvest water loss in peach fruit by enhancing cuticular wax accumulation and inhibiting pectin degradation.

Postharvest water loss significantly affects fruit storability. Hydrogen sulfide (H₂S) is an emerging gaseous signaling molecule with demonstrated preservation potential for harvested fruit; however, the mechanism by which it controls postharvest water loss needs further investigation. In this study, NaHS (9 mmol·L⁻¹) was applied to peach fruit (Prunus persica (L.) Batsch cv. 'Hujing') to investigate changes in cuticular wax at 5 d after treatment, as well as pectin degradation and cell wall characteristics during storage. NaHS treatment increased total cuticular wax content from 21.30 ± 2.64 μg·cm⁻² to 28.07 ± 1.20 μg·cm⁻² and alkane content from 9.51 ± 1.01 μg·cm⁻² to 11.43 ± 0.41 μg·cm⁻² at 5 days after treatment, resulting in a more continuous and compact wax layer on the fruit surface. Also, NaHS treatment suppressed pectin-degrading enzyme activities, with the strongest reduction in polygalacturonase activity observed at 1 d after treatment (74.0%) and a significant reduction in pectin methylesterase activity already evident at 0 d after treatment (31.5%), and slowed the conversion of sodium carbonate-soluble and chelator-soluble pectins into water-soluble pectin. Together, these results indicate that NaHS treatment alleviates postharvest water loss in peaches by enhancing epidermal wax accumulation and delaying cell wall degradation. These findings offer new insights into the physiological role of H₂S in postharvest fruit preservation.