Tomato is susceptible to chilling injury during cold storage. In this study, we found that low temperature promoted the expression of brassinosteroid (BR) biosynthetic genes in tomato fruits. The overexpression of SlCYP90B3 (SlCYP90B3-OE), a key BR biosynthetic gene, alleviated the chilling injury with decreased electrical conductivity and malondialdehyde. In SlCYP90B3-OE tomato fruits, the activities of antioxidant enzymes, including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), were markedly increased, while the activity of membranous lipolytic enzymes, lipoxygenase (LOX), and phospholipase D (PLD), were significantly decreased when compared with the wild-type in response to cold storage. Furthermore, the expression level of the cold-response-system component, SlCBF1, was higher in SlCYP90B3-OE fruits than in the wild-type fruits. These results indicated that SlCYP90B3 might be involved in the chilling tolerance of tomato fruits during cold storage, possibly by regulating the antioxidant enzyme system and SlCBF1 expression.

Chitosan oligosaccharide (COS), a degradation product of chitosan, is easily accessible, highly bioactive, non-toxic, and well-soluble in water. The effects of COS on the qualitative attributes of tomato fruits were investigated in the current study. COS was administered to tomato plants (Solanum lycopersicum cv. Ruixinghongniu) by foliar spray and root irrigation in alternate cycles at concentrations of 0.5 g·L⁻¹ and 0.16 g·L⁻¹, respectively. The experimental outcomes revealed that COS treatment promoted the coloring and softening of tomato fruits. Lycopene, vitamin C, fructose, and glucose levels increased by 49.0%, 25.4%, 30.2%, and 33.4%, respectively, in COS-treated ripe fruits compared to controls. The volatile metabolome showed that COS application also increased the release of ten volatiles correlated with consumer preference (1-penten-3-one, (E)-2-pentenal, (E)-3-hexen-1-ol, (E)-2-heptenal, 2-isobutylthiazole, phenylacetaldehyde, 2-phenylethanol, 6-methyl-5-hepten-2-one, 6-methyl-5-hepten-2-ol, and β-ionone), contributing to an improved tomato flavor. Moreover, increased transcript levels of genes participating in ethylene biosynthesis, perception, and response along with enhanced ethylene production were observed in COS-treated fruits, suggesting that COS may regulate tomato fruit quality via the ethylene pathway. Taken together, our results indicated that the pre-harvest application of COS could improve tomato fruit quality attributes.

Peel glossiness is an important commercial trait of eggplant (Solanum melongena L.). In this study, two eggplant-inbred lines with different levels of peel glossiness were used to identify genes related to peel glossiness. Paraffin section analysis showed that increased wax thickness and wrinkles on the wax surface of eggplant peels decreased glossiness. Differential gene expression related to eggplant peel glossiness was analyzed by comparing the transcriptomes of eggplant peels with different gloss levels and at different developmental stages. The results identified 996 differentially expressed genes (DEGs), including 502 upregulated and 494 downregulated genes, possibly related to eggplant peel glossiness. GO enrichment and KEGG enrichment analyses revealed that the DNA replication pathway (GO:0003688, GO:0006270) and the photosynthesis pathway (map00195) were downregulated and thus may be associated with reduced eggplant peel glossiness. Expression level analysis of eggplant peels with different glossiness levels revealed that a C2H2 transcription factor gene, two ERF transcription factor genes, one long-chain acyl-CoA synthetase gene, and four wax- or cutin-related genes may be associated with the glossiness of eggplant fruit peels. These findings will help guide future genetic improvements in eggplant peel glossiness.

Modulating nutrient-solution electrical conductivity (EC) is an important strategy for improving the fruit flavor of tomato (Solanum lycopersicum L.) in soilless culture. Previous salinity studies have typically elevated EC through NaCl supplementation, which is physiologically distinct from raising EC via basal nutrient concentrations. Moreover, whether the quality-improving effect of moderately high electrical conductivity (HEC) arises from passive osmotic concentration or active metabolic reprogramming remains unclear. Tomato cultivar ‘Hangza 602’ was grown under CK (2.0 mS cm⁻¹) and HEC (3.0 mS cm⁻¹). Fruits were sampled at mature-green, breaker, pink and red-ripe stages for integrated transcriptomic, enzymatic and metabolomic analyses. HEC increased total soluble solids across ripening stages and promoted sugar and organic acid accumulation at pink and red-ripe stages, with a greater organic-acid increment reducing the sugar–acid ratio. Sugar transporter genes were induced at the breaker stage. At the pink stage, HEC elevated the activities of phosphofructokinase, citrate synthase and NADP–malate dehydrogenase without altering sucrose-phosphate synthase, indicating enhanced catabolic flux rather than sucrose biosynthesis. Sugars and citric acid accumulated persistently, whereas malic acid rose transiently then declined at red-ripe. Multiple downstream pathways were altered in HEC-treated red-ripe fruits. Collectively, HEC initiates stage-specific carbon-metabolic reprogramming combining osmotic and active effects, providing experimental insights for precision EC management in protected tomato production. Future work will further identify key regulatory genes governing this stage-specific metabolic response and validate the combined effects of EC and other environmental factors to develop robust soilless culture strategies for flavor improvement.