There is little study on melatonin’s ability to prevent salt damage in eggplants, despite the fact that it is a strong antioxidant in plants that has been found to help mitigate a variety of adverse challenges. In this study, we used “Anhui Eggplant No.8” as the test material and simulated salt stress by irrigating the roots with 150 mmol·L NaCl solution. Subsequently, we treated the eggplants with different concentrations of exogenous melatonin (0, 50, 100, 150, 200, 250 μmol·L) and assessed the plant traits and an array of physiological and biochemical indices following melatonin application to observe the impact of salt stress. Our study results indicate that exogenous melatonin at a concentration of 200 μmol·L can significantly alleviate the inhibition of eggplant photosynthesis under salt stress by increasing the content of chlorophyll in leaves and the activity of antioxidant enzymes. This leads to a notable increase in the levels of non-enzyme antioxidants and osmotic regulatory substances. As a result, the antioxidant capacity of the eggplants is enhanced, the degree of membrane lipid peroxidation is reduced, and the growth of eggplant seedlings under salt stress is effectively promoted, thereby strengthening the salt tolerance of eggplant seedlings. Fluorescence quantitative data analysis indicates that SmCAT4 is indeed a gene that positively regulates salt stress. However, in the SmPPO family, we did not find any genes that respond to salt stress. This research provides a theoretical foundation for improving the yield productivity and quality of eggplants under protected farming by clarifying the physiological mechanism by which melatonin controls the salt tolerance of eggplant seedlings.

The BBX gene family functions as a key transcription factor implicated in plant growth, development, and stress responses. However, research on this gene family in melon remains absent. In the present study, we identified 19 BBX family genes within the melon genome, distributed across chromosomes 1, 2, 3, 4, 5, 7, 8, 10, 11, and 12. Phylogenetic analysis categorized these genes into five distinct subfamilies, with notable similarities observed in gene structure and conserved motifs among members of the same subfamily. Synteny analysis revealed seven syntenic relationships among melon BBX genes, 17 between melon and Arabidopsis, and one between melon and rice. Reanalysis of transcriptome data indicated that certain BBX genes exhibit high expression levels across various tissues and developmental stages of fruits, while others display tissue specificity. Under both abiotic and biotic stress conditions, genes such as CmBBX3, CmBBX5, CmBBX2, CmBBX18, CmBBX15, and CmBBX11 demonstrated significant differential expression, highlighting their critical roles in melon growth and development. Additionally, RT-qPCR analysis was conducted to examine the expression levels of melon BBX genes at different time points under salt stress, further validating the transcriptome data. This study provides a theoretical foundation for future molecular breeding efforts in melon.

Peppers are widely cultivated around the world, yet they suffer from infections caused by Phytophthora capsici fungi throughout the year, which severely impacts their yield. The β-1,3-glucanase gene has been shown in previous studies to significantly enhance plants’ ability to cope with both biotic and abiotic stresses, including fungal infections. However, its function in peppers has not been reported. In this study, 80 CaBG genes were initially identified, before being filtered down to 54 CaBGs in peppers, and analyses conducted on the physicochemical properties, chromosomal localization, phylogenetic tree relationships, synteny, promoters, and gene expression levels of the BG gene family. The results indicated that these 54 CaBG genes are located on 12 chromosomes. Phylogenetic tree analysis classified the CaBGs into three subfamilies, α, β, and γ, each with its own specific functions, with the γ subfamily being associated with disease resistance in peppers. Synteny analysis showed that CaBG genes are relatively conserved and have not undergone extensive whole-genome duplication events. Promoter analysis indicated that CaBGs are induced by plant hormones and various external stressors. Transcriptomic and RT-qPCR analyses revealed that the CaBG7 and CaBG12 genes were significantly activated following infection by P. capsici, with the expression levels of these two genes being markedly higher in resistant plants compared to susceptible ones. Based on the phylogenetic tree and gene expression analysis, we propose that CaBG7 and CaBG12 may be key genes for disease resistance in chili peppers. This study provides a theoretical basis for breeding P. capsici-resistant chili peppers by molecular breeding methods.