The nuclear factor Y (NF-Y) transcription factor contains three subfamilies: NF-YA, NF-YB, and NF-YC. The NF-Y family have been reported to be key regulators in plant growth and stress responses. However, little attention has been given to these genes in melon (Cucumis melo L.). In this study, twenty-five NF-Ys were identified in the melon genome, including six CmNF-YAs, eleven CmNF-YBs, and eight CmNF-YCs. Their basic information (gene location, protein characteristics, and subcellular localization), conserved domains and motifs, and phylogeny and gene structure were subsequently analyzed. Results showed highly conserved motifs exist in each subfamily, which are distinct between subfamilies. Most CmNF-Ys were expressed in five tissues and exhibited distinct expression patterns. However, CmNF-YA6, CmNF-YB1/B2/B3/B8, and CmNF-YC6 were not expressed and might be pseudogenes. Twelve CmNF-Ys were induced by cold stress, indicating the NF-Y family plays a key role in melon cold tolerance. Taken together, our findings provide a comprehensive understanding of CmNF-Y genes in the development and stress response of melon and provide genetic resources for solving the practical problems of melon production.

Salt and osmotic stress seriously restrict the growth, development, and productivity of horticultural crops in the greenhouse. The papain-like cysteine proteases (PLCPs) participate in multi-stress responses in plants. We previously demonstrated that salt and osmotic stress affect cysteine protease 15 of pepper (Capsicum annuum L.) (CaCP15); however, the role of CaCP15 in salt and osmotic stress responses is unknown. Here, the function of CaCP15 in regulating pepper salt and osmotic stress resistance was explored. Pepper plants were subjected to abiotic (sodium chloride, mannitol, salicylic acid, ethrel, methyl jasmonate, etc.) and biotic stress (Phytophthora capsici inoculation). The CaCP15 was silenced through the virus-induced gene silencing (VIGS) and transiently overexpressed in pepper plants. The full-length CaCP15 fragment is 1568 bp, with an open reading frame of 1032 bp, encoding a 343 amino acid protein. CaCP15 is a senescence-associated gene 12 (SAG12) subfamily member containing two highly conserved domains, Inhibitor 129 and Peptidase_C1. CaCP15 expression was the highest in the stems of pepper plants. The expression was induced by salicylic acid, ethrel, methyl jasmonate, and was infected by Phytophthora capsici inoculation. Furthermore, CaCP15 was upregulated under salt and osmotic stress, and CaCP15 silencing in pepper enhanced salt and mannitol stress resistance. Conversely, transient overexpression of CaCP15 increased the sensitivity to salt and osmotic stress by reducing the antioxidant enzyme activities and negatively regulating the stress-related genes. This study indicates that CaCP15 negatively regulates salt and osmotic stress resistance in pepper via the ROS-scavenging.

Actinidia deliciosa is a globally important economic fruit crop, and its fruit quality and yield are profoundly influenced by light and environmental conditions. Sucrose phosphate synthase (SPS), a key rate-limiting enzyme in the sucrose biosynthesis pathway, plays a central role in regulating carbon metabolism and sucrose accumulation in plants. However, comprehensive studies of the SPS gene family in A. deliciosa are still lacking, particularly regarding its expression in response to different light qualities. In this study, genome-wide identification of the SPS gene family in A. deliciosa was conducted using bioinformatics approaches. A total of 31 SPS genes were identified and named AdSPS1 to AdSPS31 on the basis of their chromosomal positions. The encoded proteins were predicted to be acidic, hydrophilic, and primarily localized in the chloroplast. All the AdSPS proteins contained the conserved domains Sucrose_synth, Glyco_trans_1, and S6PP, indicating potential roles in sucrose metabolism. Phylogenetic analysis classified the 31 AdSPS members into three subfamilies, A, B, and C, comprising 20, 5, and 6 members, respectively. Collinearity analysis revealed extensive syntenic relationships among AdSPS genes across different chromosomes, suggesting that gene duplication events contributed to the expansion of this gene family. Promoter cis-acting element analysis revealed that light-responsive elements were the most abundant among all the detected elements in the upstream regions of the AdSPS genes, implying potential regulation by light signals. Different light qualities significantly affected the contents of sucrose, glucose, and fructose, as well as SPS activity in kiwifruit leaves, with the highest activity observed under the R3B1 (red–blue light 3:1) treatment. Spearman’s correlation analysis indicated that AdSPS3 was significantly negatively correlated with sucrose, fructose, glucose, and SPS activity, suggesting a potential role in negatively regulating sugar accumulation in kiwifruit leaves, whereas AdSPS12 showed positive correlations with these parameters, implying a role in promoting sucrose synthesis. To further explore the light response of the AdSPS genes, eight representative members were selected for qRT‒PCR analysis under red light, blue light, and combined red‒blue light treatments. These results demonstrated that light quality significantly influenced SPS gene expression. Specifically, AdSPS6 and AdSPS24 were highly responsive to R1B1 (1:1 red‒blue light), AdSPS9 was significantly upregulated under R6B1 (6:1 red‒blue light), AdSPS21 was strongly induced by blue light, and AdSPS12 expression was suppressed. This study systematically identified and analyzed the SPS gene family in A. deliciosa, revealing its structural characteristics and light-responsive expression patterns. These findings suggest that AdSPS genes may play important roles in light-regulated carbon metabolism. These results provide a theoretical foundation and valuable genetic resources for further elucidating the molecular mechanisms of sucrose metabolism and light signal transduction in kiwifruit.