Metabolic diversity, biosynthetic pathways, and metabolite biomarkers analysed via untargeted metabolomics and the antioxidant potential reveal for high temperature tolerance in tomato hybrid

High-temperature tolerant varieties/hybrids of tomato overcome stress-related changes due to their intrinsic cellular metabolic capabilities. We have used untargeted metabolite profiling and comparative biochemical and biological analyses of high temperature tolerant (HTT) tomato hybrid VRNTH18283 and sensitive (HTS) VRNTH19072 to decipher altered metabolic pathways and biomarker metabolites which were linked with enhanced antioxidant activity in HTT fruits. Parameters like fruit weight, yield per plant and key biochemical determinants viz. total soluble sugar (TSS), titratable acidity, ascorbic acid and lycopene content were significantly high in HTT hybrid compared to HTS. Metabolomics revealed upregulated metabolite diversity in HTT fruit extract (11453 m/z features) as compared to 8834 m/z features in HTS. Statistical analysis revealed 423 differentially up-regulated and 410 down-regulated metabolite features. Multivariate data analyses showed sample discrimination based on distinct phytochemical diversification. Functionally annotated metabolite features showed enrichment in metabolic pathways including linoleic and linolenic acid metabolism, monoterpenoids biosynthesis and degradation, cutin, suberin and wax biosynthesis, and sphingolipids metabolism. Metabolite features were categorized in benzamides, amino acids, sugars, nucleotides, sterols, glycosides, phenylacetaldehydes, indoles, tryptamines and organic acids as major compound classes. Among 22 potentially discriminatory metabolites obtained from OPLS-DA model, all including prominently abundant solasodine, thiamine diphosphate, L-tryptophan, folic acid, lycopene, dihydrozeatin, myricetin, tomatidine, chlorogenic acid and α-tocotrienol were classified as metabolite biomarkers and were correlated with enhanced antioxidant activity. The study revealed that the altered physicochemical profile, increased metabolite compositional diversity and discriminatory metabolite biomarkers are liable for improved performance of the hybrid HTT VRNTH18283 against the negative impact of high temperature in comparison to HTS VRNTH19072.