Application of 5-aminolevulinic acid promotes ripening and accumulation of primary and secondary metabolites in postharvest tomato fruit

Abstract

5-Aminolevulinic acid (ALA) plays a vital role in promoting plant growth, enhancing stress resistance, and improving fruit yield and quality. In the present study, tomato fruits were harvested at mature green stage and sprayed with 200 mg L–1 ALA on fruit surface. During ripening, the estimation of primary and secondary metabolites, carotenoids, and chlorophyll contents, and the expression levels of key genes involved in their metabolism were carried out. The results showed that ALA significantly promoted carotenoids accumulation by upregulating the gene expression levels of geranylgeranyl diphosphate synthase (GGPPS, encoding geranylgeranyl diphosphate synthase), phytoene synthase 1 (PSY1, encoding phytoene synthase), phytoene desaturase (PDS, encoding phytoene desaturase), and lycopeneβ-cyclase (LCYB, encoding lycopene β-cyclase), whereas chlorophyll content decreased by downregulating the expression levels of Mg-chelatase (CHLH, encoding Mg-chelatase) and protochlorophyllide oxidoreductase (POR, encoding protochlorophyllide oxidoreductase). Besides, the contents of soluble solids, vitamin C, soluble protein, free amino acids, total soluble sugar, organic acid, total phenol, and flavonoid were increased in ALA-treated tomato fruit, but the fruit firmness was decreased. These results indicated that the exogenous ALA could not only promote postharvest tomato fruit ripening but also improve the internal nutritional and flavor quality of tomato fruit.

The Crucial Role of SlGSNOR in Regulating Postharvest Tomato Fruit Ripening

“…Thus, coloration is a crucial step during fruit ripening and fruit postharvest storage. The transition of tomato fruit skin color is always conducted via the destruction of chlorophylls and the accumulations of new pigments, such as carotenoid, lycopene, and anthocyanins [ 27 ]. NO can postpone fruit coloration through judging pigment biosynthesis.…”

“…Meanwhile, the impacts of GSNOR and NO on these nutrients may be different upon different treatment conditions and different storage periods. It has been found that phenolic acids and flavonoids are essential compounds for sustaining great quality in postharvest fruit [ 27 ]. Also, they are a crucial source for tomato flavor construction [ 42 ].…”

A Comprehensive Evaluation of Tomato Fruit Quality and Identification of Volatile Compounds

“…Firstly, the juice of a tomato fruit was dropped on a digital refractometer PAL-1 (Atago, Tokyo, Japan) and the value of the soluble solids were measured [ 23 ]. The vitamin C content of the fruits was measured using the 2,6-dichloroindophenol staining method in conjunction with a spectrophotometric measurement at 500 nm [ 24 ].…”

“…The detection wavelength was 210 nm, and the column temperature was 30 °C. The organic acid contents were determined according to the concentration curves of citric acid, malic acid, tartaric acid, fumaric acid, α-ketoglutaric acid, and oxalic acid standards [ 23 ].…”

Effects of L-Cysteine and γ-Aminobutyric Acid Treatment on Postharvest Quality and Antioxidant Activity of Loquat Fruit during Storage

“…Recently, natural amino acids have been widely applied in agricultural production as safe exogenous treatments. Exogenous amino acid treatment can regulate growth and development and can improve the quality of fruits and vegetables [ 7 ] and enhance the stress resistance of fruits [ 8 ].…”