Tracing Phenolic Metabolism inVitis viniferaBerries with¹³C₆-Phenylalanine: Implication of an Unidentified Intermediate Reservoir

Abstract

Understanding the regulation of phenolic compounds in agricultural products has been a topic of great interest. In V. vinifera berries, phenolics are responsible for important sensory and functional characteristics. To elucidate the ripening profile of phenolic compounds in Cabernet Sauvignon berries, the stable-isotope tracer l-phenyl-(13)C6-alanine (Phe(13)) was incorporated in situ, and the development of labeled and unlabeled phenolics was tracked in the vineyard at different stages of maturity over two vintages. Phenolic profiles during ripening were consistent with previous research. However, individual anthocyanins accumulated with different profiles during ripening; malvidin species continually climbed in concentration, whereas other anthocyanins tended to plateau or drop near the end of the growing season. The isotopic label was predominantly incorporated into anthocyanins, presumably because of their dominant accumulation during ripening. Notably, the incorporation of label continued long after levels of Phe(13) had dropped to below 1 nmol/berry, preventing an accurate assessment of the hypothesized turnover of anthocyanins. Although our tracer did not perform exactly as we had expected, the results of this study suggest the presence of a previously unreported pool of substrate in the phenolic pathway.

Effect of nitrogen regulation on berry quality and flavonoids during veraison stage

“…Moreover, the total anthocyanin content in grape skins under urea treatment was the highest, which was similar to Javier et al., ( 2017 ). However, this result is in contrast with the research results of Chassy et al., ( 2014 ). Due to different vineyard environmental factors and cultivation management measures, nitrogen types also have different effects on anthocyanins, so the effect of phenylalanine is sometimes better than that of urea (Javier et al., 2017 ; Riccardo et al., 2013 ).…”

Using foliar nitrogen application during veraison to improve the flavor components of grape and wine

“…107 Therefore, nitrogenous fertilizer application may improve the aromatic compounds derived from amino acid metabolism. Moreover, Chassy et al 110 proposed that phenylalanine could be accumulated in grape as an intermediate substrate pool (i.e. phenolamides) and be further metabolized under requirements from different metabolic pathways.…”

Phenylalanine promotes phenolic compounds and quality of Qızıl Uzum grape (Vitis vinifera L.) fruit by regulating expression patterns of PAL and CHS genes and modulating the antioxidant system

“…Due to the participation of phenylalanine in the biosynthesis pathway of bioactive compounds, phenylalanine is considered a source of grape phenol-derived compounds, including anthocyanins, hydroxy cinnamates, avonols, avan-3ols, tannins, and stilbenes 4 . All of these compounds are synthesized from phenylalanine via the phenylpropanoid pathway.…”

“…It is noted that phenylalanine is found as an abundant amino acid in grapes and is described in the rst stage of the phenylpropanoid pathway, the precursor of various phenolic compounds 3 . It is well demonstrated that apart from the fact that phenylalanine incorporation into grape berries in uences berry phenolic metabolism, also it is detected as a positive compound for grape and wine aromatic characteristics 4 , respect to these facts, this aromatic amino acid drastically participates in the production of aromatic compounds and particular antioxidant components 5 .…”