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.

Fruit color is a key quality trait in cherry tomato (Solanum lycopersicum) and an important factor influencing consumer purchasing decisions. Various pigments, including flavonoids, carotenoids, and chlorophylls, form the biochemical basis of fruit coloration, imparting vivid colors such as red, yellow, orange, and green. Flavonoids and carotenoids are also essential nutritional components in cherry tomato, directly influencing their commercial value, while chlorophylls are crucial for photosynthesis and fruit development. However, conventional tomato varieties typically contain insufficient flavonoid levels to meet human dietary requirements. In this study, we quantified flavonoids, carotenoids, and chlorophyll a and b in ten high-flavonoid cherry tomato cultivars and investigated the relationships between fruit color and pigment content. The results revealed that red and orange tomato varieties contained higher flavonoid and carotenoid levels than yellow varieties, while green tomatoes exhibited elevated chlorophyll content. Yellow varieties showed the maximum L* (lightness) value. Flavonoid and carotenoid contents were significantly positively correlated with a* (red-green axis) and a*/b* (yellow-blue axis) values but negatively correlated with hue angle, whereas chlorophyll content showed no significant correlations with color parameters. Our findings provide guidance for evaluating the nutritional value of cherry tomatoes based on pigmentation.

Fruit color is a key quality trait in cherry tomato (Solanum lycopersicum) and an important factor influencing consumer purchasing decisions. Various pigments, including flavonoids, carotenoids, and chlorophylls, form the biochemical basis of fruit coloration, imparting vivid colors such as red, yellow, orange, and green. Flavonoids and carotenoids are also essential nutritional components in cherry tomato, directly influencing their commercial value, while chlorophylls are crucial for photosynthesis and fruit development. However, conventional tomato varieties typically contain insufficient flavonoid levels to meet human dietary requirements. In this study, we quantified flavonoids, carotenoids, and chlorophyll a and b in ten high-flavonoid cherry tomato cultivars and investigated the relationships between fruit color and pigment content. The results revealed that red and orange tomato varieties contained higher flavonoid and carotenoid levels than yellow varieties, while green tomatoes exhibited elevated chlorophyll content. Yellow varieties showed the maximum L* (lightness) value. Flavonoid and carotenoid contents were significantly positively correlated with a* (red-green axis) and a*/b* (yellow-blue axis) values but negatively correlated with hue angle, whereas chlorophyll content showed no significant correlations with color parameters. Our findings provide guidance for evaluating the nutritional value of cherry tomatoes based on pigmentation.

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.