Profiling of primary metabolites and flavonols in leaves of two table grape varieties collected from semiarid and temperate regions.

Cultivation of grapes in West Bank - Palestine is very old and a large number of grape varieties exist as a result of continuous domestication over thousands of years. This rich biodiversity has highly influenced the consumer behavior of local people, who consume both grape berries and leaves. However, studies that address the contents of health-promoting metabolites in leaves are scarce. Accordingly the aim of this study is to assess metabolite levels in leaves of two grape varieties that were collected from semiarid and temperate regions. Metabolic profiling was conducted using GC-MS and LC-MS. The obtained results show that abiotic stresses in the semiarid region led to clear changes in primary metabolites, in particular in amino acids, which exist at very high levels. By contrast, qualitative and genotype-dependent differences in secondary metabolites were observed, whereas abiotic stresses appear to have negligible effect on the content of these metabolites. The qualitative difference in the flavonol profiles between the two genotypes is most probably related to differential expression of specific genes, in particular flavonol 3-O-rhamnosyltransferase, flavonol-3-O-glycoside pentosyltransferases and flavonol-3-O-d-glucosidel-rhamnosyltransferase by 'Beituni' grape leaves, which led to much higher levels of flavonols with rutinoside, pentoside, and rhamnoside moieties with this genotype.