Vitis vinifera berry metabolic composition during maturation: Implications of defoliation

Abstract

Leaves are an important contributor toward berry sugar and nitrogen (N) accumulation, and leaf area, therefore, affects fruit composition during grapevine (Vitis vinifera) berry ripening. The aim of this study was to investigate the impact of leaf presence on key berry quality attributes in conjunction with the accumulation of primary berry metabolites. Shortly after the start of véraison (berry ripening), potted grapevines were defoliated (total defoliation and 25% of the control), and the accumulation of berry soluble solids, N and anthocyanins were compared to that of a full leaf area control. An untargeted approach was undertaken to measure the content in primary metabolites by gas chromatography/mass spectrometry. Partial and full defoliation resulted in reduced berry sugar and anthocyanin accumulation, while total berry N content was unaffected. The juice yeast assimilable N (YAN), however, increased upon partial and full defoliation. Remobilized carbohydrate reserves allowed accumulation of the major berry sugars during the absence of leaf photoassimilation. Berry anthocyanin biosynthesis was strongly inhibited by defoliation, which could relate to the carbon (C) source limitation and/or increased bunch exposure. Arginine accumulation, likely resulting from reserve translocation, contributed to increased YAN upon defoliation. Furthermore, assessing the implications on various products of the shikimate pathway suggests the C flux through this pathway to be largely affected by leaf source limitation during fruit maturation. This study provides a novel investigation of impacts of leaf C and N source presence during berry maturation, on the development of key berry quality parameters as underlined by alterations in primary metabolism.

Effects of Vine Water Status on Yield Components, Vegetative Response and Must and Wine Composition

“…Reductions in shoot weight are accentuated by long-term water deficit [6]. Thus, water deficit has a cumulative effect, probably due to reduced starch and sucrose accumulation in the perennial organs [65][66][67]. This is important since the sugars accumulated in the trunk and roots are the first carbohydrates to be used during the following spring's growth.…”

Ethephon‐induced leaf senescence increases the concentration of yeast‐assimilable nitrogen in grape must (Vitis viniferacv. Riesling)

“…The impact of leaf senescence on berry YAN is further indicated by the parallel timing between the respective beginning of leaf senescence (and thus the N remobilisation from the leaf) and the increase of the FAN value in the berries in both the senescence treatments. No causal relationship, however, can be proven from the parallel timing in the data alone; a rearrangement of reserves as the cause of the N increase in the berry as described by Rossouw et al (2018) is also conceivable. However, as the main reserve bodies (roots, stem) also show an increase in N concentration between veraison and harvest (Verdenal et al 2021), they generally appear to be N sinks rather than N sources during this stage.…”

Exploration of Global and Specialized Near-Infrared Calibrations for the Quantification of Nutritional Content in Grapevine Organs, Berry Phenological Stages, and Shoot Lignification

“…4 Additionally, vine growth, berry sugar accumulation, and anthocyanin biosynthesis are influenced by carbon concentrations. 8,13,14 Various important chemical reactions are affected by the hydrogen content, including respiration and carbohydrate accumulation. Furthermore, hydrogen is involved in the formation of multiple compounds, such as sugars, starch, amino acids, and organic acids.…”