Light-induced Variation in Phenolic Compounds in Cabernet Sauvignon Grapes (Vitis vinifera L.) Involves Extensive Transcriptome Reprogramming of Biosynthetic Enzymes, Transcription Factors, and Phytohormonal Regulators

Abstract

Light environments have long been known to influence grape (Vitis vinifera L.) berry development and biosynthesis of phenolic compounds, and ultimately affect wine quality. Here, the accumulation and compositional changes of hydroxycinnamic acids (HCAs) and flavonoids, as well as global gene expression were analyzed in Cabernet Sauvignon grape berries under sunlight exposure treatments at different phenological stages. Sunlight exposure did not consistently affect the accumulation of berry skin flavan-3-ol or anthocyanin among different seasons due to climatic variations, but increased HCA content significantly at véraison and harvest, and enhanced flavonol accumulation dramatically with its timing and severity degree trend. As in sunlight exposed berries, a highly significant correlation was observed between the expression of genes coding phenylalanine ammonia-lyase, 4-coumarate: CoA ligase, flavanone 3-hydroxylase and flavonol synthase family members and corresponding metabolite accumulation in the phenolic biosynthesis pathway, which may positively or negatively be regulated by MYB, bHLH, WRKY, AP2/EREBP, C2C2, NAC, and C2H2 transcription factors (TFs). Furthermore, some candidate genes required for auxin, ethylene and abscisic acid signal transductions were also identified which are probably involved in berry development and flavonoid biosynthesis in response to enhanced sunlight irradiation. Taken together, this study provides a valuable overview of the light-induced phenolic metabolism and transcriptome changes, especially the dynamic responses of TFs and signaling components of phytohormones, and contributes to the further understanding of sunlight-responsive phenolic biosynthesis regulation in grape berries.

Dissecting the Variations of Ripening Progression and Flavonoid Metabolism in Grape Berries Grown under Double Cropping System

“…The metabolism of flavonoids in grapevine is closely correlated with environmental stresses, variety and tissue, developmental cues, and phytohormone regulation. There have been many transcriptomic studies showing the dynamics of gene expression and flavonoid accumulation in response to internal and external stimuli ( Degu et al, 2014 ; Carbonell-Bejerano et al, 2014 ; Li et al, 2014 ; Savoi et al, 2016 ; Blanco-Ulate et al, 2017 ; Lecourieux et al, 2017 ; Sun et al, 2017 ). Here, a comparative parallel analysis was conducted on grapes grown under a double cropping system in two cultivars.…”

“…Since the first report of the draft genome sequence of the Pinot Noir grapevine ( Jaillon et al, 2007 ), genome-wide transcriptome research revealing the regulation of berry ripening and its associated metabolic processes has become a hot topic ( Fabres et al, 2017 ; Wong and Matus, 2017 ). Transcriptomic analyses also provide a comprehensive approach to study the transcriptional responses of grapes to changing environment conditions ( Sun et al, 2017 ). Water deficit activates the expression of phenylpropanoid pathway transcripts, which increases flavonoid content in wine grape ( Grimplet et al, 2007 ; Deluc et al, 2009 ; Savoi et al, 2016 ).…”

VviERF6Ls: an expanded clade in Vitis responds transcriptionally to abiotic and biotic stresses and berry development

“…CS berries exposed to varying light intensity through leaf removal or leaf movement at veraison demonstrated reduced VviERF6L12 transcript abundance in de-seeded berries (pulp and skin only) at late veraison and harvest. The majority of the other VviERF6Ls (all with lower transcript abundance than VviERF6L12) had enhanced transcript accumulation at harvest (particularly with leaf removal) relative to control conditions in which no leaves were (re)moved [41]…”

Effects of bagging or the combination of umbrella and bag treatments on anthocyanin accumulation in the berry skin of ‘Kyoho’ (Vitis labruscana) Grape

“…Anthocyanins are influenced by environmental factors and viticultural practices. On grapes, there have been a number of reports of light exposure or shading affecting anthocyanin accumulation (Matus et al, 2009;Li et al, 2013;Sun et al, 2017).…”