First quantitative assessment of growth, sugar accumulation and malate breakdown in a single ripening berry

Abstract

Background: Most approaches to grape physiology accept that the berry and the future harvest should display identical developmental features, which obviously requires synchronised fruits.Aims: Rejecting this assumption compels to revisit the kinetic and metabolic bases of berry ripening.Methods and Results: Two to three thousand berries were individually analysed for sugar, malate and weight. The huge heterogeneity in sugar and malic acid concentrations among fruits was mostly explained by time lags in the onset of sugar storage, which proved nearly as long as the second growth phase. Individual berries from different cultivars displayed similar kinetics following the normalisation of their maximal volume. Phloem sucrose unloading started at its maximum speed at softening, but growth resumed one week later. Four hexoses accumulated per malic acid, which was oxidised during the first two weeks of ripening, and then malate breakdown stopped without affecting sugar accumulation. Sugar and water accumulation were simultaneously arrested four weeks after softening, at 0.9 M hexose, at which point sugar concentration continued through water losses.Conclusions: The accepted sequential random sampling methods representative of average fruit and future wine compositions have led to a scrambled vision of grape developmental biology, presenting serious kinetic and composition biases. Single berry composition provides first quantitative evidence for the induction of a dominant H+/sucrose exchange on the tonoplast, which is first electro-neutralised by malate breakdown, then by ATP demanding H+ recirculation, in line with functional and molecular studies.Significance of the Study: The kinetics of single berry ripening are presented for the first time. A more reliable and reproducible model of berry growth, sugar import and malate breakdown is shown here, which have definitively been improved from a quantitative point of view. It illustrates that the temporal structure of a berry population may largely contribute to future wine quality, in addition to metabolic plasticity, thereby providing another target for the impact of GxE interaction. In this respect, addressing the structure of berry cohorts may provide a new approach regarding the developmental biology/terroir nexus.

The application of ozonated water rearranges the Vitis vinifera L. leaf and berry transcriptomes eliciting defence and antioxidant responses

“…Mature leaf samples (L) displayed a comparable amount of soluble sugars to BR, with a two-fold lower malate concentration, indicating strong differentiation between the source (leaves) and sink (berries) organs. Thanks to the measurements of sugars and acids, it was possible to gather synchronised samples 26 for further RNA-Seq analysis with the aim to reduce biases in gene expression caused by the natural developmental asynchrony of grapevine berries and focus only on the early transcriptomic changes triggered by the ozonated water treatment. Indeed, biological triplicates were selected at the same sugar (glucose + fructose) concentrations for control (C) and ozonated water treatment (OW), namely 158 mM in L, 291 mM in BR, and 864 mM in MR (Fig.…”

Grape Berry Secondary Metabolites and Their Modulation by Abiotic Factors in a Climate Change Scenario–A Review

“…Several molecular studies tried to address the complex issue of grape ripening on a single berry scale (Gouthu et al, 2014 ; Rienth et al, 2014b , 2016 ; Shahood et al, 2015 , 2020 ; Carbonell-Bejerano et al, 2016 ; Rösti et al, 2018 ). For instance, Carbonell-Bejerano et al ( 2016 ) performed berry density sorting by berry flotation in NaCl solutions and assessed the transcriptome of different berry ripening groups and showed that gene expression profiles clearly relate with ripening progression of different sorted berry groups.…”

The Application of Ozonated Water Rearranges the Transcriptome of the Vitis Vinifera L. Fruit

“…Mature leaf samples (L) displayed a comparable amount of soluble sugars to BR, with a two-fold lower malate concentration, indicating strong differentiation between the source (leaves) and sink (berries) organs. Thanks to the measurements of sugars and acids, it was possible to gather synchronised samples 24 for further RNA-Seq analysis with the aim to reduce biases in gene expression caused by the natural developmental asynchrony of grapevine berries and focus only on the early transcriptomic changes triggered by the ozonated water treatment. Indeed, biological triplicates were selected at the same sugar (glucose + fructose) concentrations for control (C) and ozonated water treatment (OW), namely 158 mM in L, 291 mM in BR, and 864 mM in MR (Fig.…”