Variation of Growth-to-Ripening Time Interval Induced by Abscisic Acid and Synthetic Auxin Affecting Transcriptome and Flavor Compounds in Cabernet Sauvignon Grape Berry.

Lei He,Zhi-Yuan Ren,Qiu-Hong Pan,Ya-Qun Fu,Yue Li,Nan Meng,Yu Wang

doi:10.3390/plants9050630

Abstract

Abscisic acid (ABA) and auxin are important hormones controlling the ripening progression of grape berry, and both the initiation and duration of ripening can dramatically affect the berry quality. However, the responses of flavor compounds to the hormones are inadequately understood. In this study, ABA and synthetic auxin α-naphthaleneacetic acid (NAA) were sprayed on Cabernet Sauvignon berries before véraison, and comparative transcriptomic and metabolic analysis were conducted to investigate the influence on berry quality-related metabolites. The 1000 mg/L ABA (ABA1000) and 200 mg/L NAA (NAA200) treated grapes exhibited shorter and longer phenological intervals compared to the control, respectively. The transcriptomic comparison between pre-véraison and véraison revealed that the varied ripening initiation and duration significantly affected the expression of genes related to specific metabolism, particularly in the biosynthetic metabolism of anthocyanin and volatile compounds. The up-regulated VviF3’H in both ABA1000-treated and NAA200-treated berries increased the proportion of 3′-substituted anthocyanins, and the 3′5′-substituted anthocyanins were largely reduced in the NAA200-treated berries. Concurrently, VviCCD4a and VviCCD4b were up-regulated, and the norisoprenoids were correspondingly elevated in the NAA200-treated berries. These data suggest that ABA and NAA applications may be useful in controlling the ripening and improving the flavor of the grape berry.

Highlights

Timing and rate of ripening are key factors in grape berries for winemaking
NAA200 caused a slower accumulation of total soluble solid (TSS) and a decline in titratable acidity (TA)
We investigated the effects of Abscisic acid (ABA) and naphthaleneacetic acid (NAA) on Cabernet Sauvignon grape berries based on E-L stage with similar sugar levels, the purpose of which is to eliminate the possible influence of sugar or other developmental characteristics

Summary

Introduction

Timing and rate of ripening are key factors in grape berries for winemaking. The composition and concentration of flavor compounds in both grapes and wine are closely associated with the ripening process and harvest maturity [1,2,3]. Immature grape berries generally contain high concentrations of organic acids, volatile C6 compounds, and methoxypyrazines, which are undesirable [4]. The ripening rate appears to affect the accumulation of flavor compounds. In warm regions with the rapid accumulation of soluble solids, harvested grape berries fail to develop adequate and desirable flavors, even with the optimum sugar/acidity ratios [5,6]. Grape berries in cooler regions need longer times to achieve industrial maturity, possibly due to the lack of adequate sunlight [7]

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