Hydrogen Sulfide: A Gaseous Molecule in Postharvest Freshness

Hydrogen sulfide (H ₂S), as a signaling molecule, is involved in the regulation of growth and development in plants. Recent studies have indicated that H ₂S also plays important roles in regulating postharvest senescence of horticultural products. The focus of this review is to summarize the synthesis of H ₂S in plants and its potential roles in alleviating the senescence of cut flowers, fruits, and vegetables during postharvest storage. During postharvest of horticultural products, H ₂S could scavenge reactive oxygen species via promoting the activity of antioxidant enzymes, thereby, sustaining the integrity of the membrane. In fruits, H ₂S effectively enhanced the tolerance of chilling by increasing the content of proline and polyphenol compounds. During postharvest storage of perishable fruits and vegetables, H ₂S significantly alleviated decay, which was caused by fungi by inhibiting the growth of fungi spores. Moreover, H ₂S interacted with other molecules synergistically (NO) or antagonistically (ethylene) to alleviate senescence of horticultural products. At the transcriptional level, H ₂S regulated the expression of senescence-related genes, which were related to degradation of proteins and chlorophyll, to delay the senescence of horticultural products. Thus, H ₂S does not only possess positive antioxidant and antifungal properties, but also significantly regulates the senescence-related gene during postharvest of horticultural products. Future studies of H ₂S in postharvest storage should focus on its molecular mechanism in the posttranslational modifications of proteins as well as its safety attributes in treated fruits and vegetables.