Overexpression of SlIMP3 regulates sugar metabolism, antioxidant activity, and fruit softening, leading to extended shelf life of tomato fruits

Abstract

During the postharvest storage of tomato fruits, they often shrink or even rot due to water loss or infection by pathogenic bacteria, leading to significant economic losses in the tomato fruit industry. Inositol monophosphatase (IMP) is involved in inositol synthesis, which serves as a precursor for the synthesis of cell wall polysaccharides and is also involved in ascorbic acid synthesis. Overexpression of SlIMP3 in tomato has been shown to delay fruit softening, but the mechanism by which SlIMP3 regulates fruit softening remains unclear. In this study, the transcriptome and metabolome of wild-type tomato fruit (WT) and SlIMP3 overexpressing tomato fruit were thoroughly analyzed at 0, 15 and 26 days of storage. A total of 83 differential metabolites were identified, and more than 2000 genes exhibited changes during storage and in SlIMP3-OE tomato fruits. KEGG pathway enrichment analysis revealed that the differential genes were mainly related to metabolic pathways and the biosynthesis of secondary metabolites. Metabolome analysis showed that various sugars (lythreon, glucose, cellobiose, allulose, etc.) and antioxidants (melatonin, 3,4-dihydroxymandelic acid, dihydroquercetin, salicylic acid) underwent significant changes during storage. Significantly, most genes associated with cell wall degradation (SlEXP1, SlPL, SlPG2, SlTBG4, SlXYL1, SlXTH5) were downregulated in SlIMP3-OE compared to the wild type. Two-omics analysis indicated that overexpression of SlIMP3 regulated the accumulation of many carbohydrates and antioxidants and the expression of related anabolic genes during storage of tomato fruits. In conclusion, overexpression of SlIMP3 affects tomato fruit softening through the modulation of carbohydrate and antioxidant metabolism, concurrently regulating the expression of genes associated with cell wall metabolism. This study provides new theoretical insights and potential methods for improving fruit quality and reducing postharvest loss.