Melatonin Promotes Post-Harvest Preservation of Cut Roses ‘Corolla’ by Facilitating the Production of Hydrogen Sulfide

Abstract

In recent years, the applications of melatonin (MT) and hydrogen sulfide (H2S) have both been proven to improve the post-harvest preservation of horticultural products. However, the specific regulatory mechanism between them in cut flower preservation remains unclear. Here, we conducted research on the combined effect of MT and H2S during the senescence of cut roses ‘Corolla’, as well as the relationship between endogenous H2S production and MT. We found that the cut roses treated with MT + H2S exhibited the longest vase life, the largest flower diameter, and the highest increase of fresh weight compared with those under MT or H2S treatment alone. We have found that both MT and H2S can inhibit the contents of the ethylene precursor ACC and the key enzymes ACS and ACO involved in ethylene synthesis in cut roses. Further investigation revealed that the application of hypotaurine (HT), a specific chemical scavenger of hydrogen sulfide (H2S), compromised the preservation of cut roses. In the combined treatment with HT and melatonin (MT), elevated levels of reactive oxygen species (ROS), along with reduced antioxidant enzyme activities and downregulated expression of associated genes, were observed. However, the combined treatment still demonstrated a superior preservative effect relative to the HT treatment alone. Conversely, MT treatment individually enhanced endogenous H2S production and upregulated the transcript levels of the H2S biosynthesis genes RhLCD and RhDCD in petal tissues. These results substantiate that MT extends the postharvest longevity of cut roses by stimulating H2S synthesis, thus counteracting oxidative damage.