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.

Pyruvate decarboxylase (PDC) is an intracellular non-oxidizing enzyme that relies on thiamine pyrophosphate (TPP), which is important for plant survival under anaerobic conditions and increasingly recognized for its role in broader stress reaction. However, the PDC gene family of tomato (Solanum lycopersicum), an important waterlogging-sensitive agricultural product, has not yet been discovered. In this study, eight SlPDC genes were discovered within the tomato genome. Gene structure analysis revealed that SlPDC members exhibited varying intron–exon configurations, with SlPDC8 possessing the most complex structure containing seven introns. Promoter analysis revealed a multitude of cis-acting elements responsive to light, hormones, and various stresses. Particularly, the promoter of SlPDC8 contains both ABRE and TGACG/CGTCA-motif. Tissue-specific expression profiles showed that SlPDC8 was mainly highly expressed in the roots. Expression profiling demonstrated that SlPDC genes respond divergently to different abiotic stresses, including salt, hydrogen peroxide (H₂O₂), drought, waterlogging, cold, heat, darkness, and UV radiation stresses. Notably, SlPDC1, SlPDC7, and SlPDC8 were significantly upregulated by waterlogging, with SlPDC8 showing the most robust induction. Functional validation through VIGS proved that SlPDC8-silenced plants exhibited significantly impaired growth, decreased photosynthetic pigment content, severe leaf wilting, and poor root development under waterlogging conditions compared to control plants. Furthermore, silencing SlPDC8 led to increased malondialdehyde (MDA) levels and decreased antioxidant enzyme activities, indicating heightened oxidative damage under waterlogging stress. We conclusively demonstrate that SlPDC8 plays a critical positive regulatory role in waterlogging tolerance by maintaining cellular homeostasis and enhancing antioxidant capacity.

This study conducted a systematic identification and functional analysis of the SlACX gene family in Solanum lycopersicum. Through genome-wide screening, a total of six SlACX members were identified, and their encoded proteins showed significant differences in physicochemical properties, suggesting potential functional differentiation. Analysis of gene structure and conserved motifs revealed that SlACXs were highly conserved in evolution, but the cis-acting elements in the promoter region were rich and diverse, suggesting that they may integrate multiple signaling pathways. Chromosomal localization and collinearity analysis revealed that gene replication events were the main driving force for family expansion, and there were key interspecific collinearity blocks with Arabidopsis thaliana and Glycine max. Expression analysis showed that SlACXs exhibited remarkable tissue specificity and strong temporal dynamic response patterns to UV, dark, ABA, MeJA, and various abiotic stresses (cold, heat, H₂O₂, PEG, and NaCl). Several genes (such as SlACX1, SlACX3, SlACX4, and SlACX5) exhibited consistently high expression levels under various stress conditions, underscoring their potential role as central regulatory hubs.