Quantifying phenotypic plasticity of berry traits using an allometric-type approach: A case study on anthocyanins and sugars in berries of Cabernet Sauvignon

Abstract

In this paper we advance a novel allometric‐type approach to quantify the stability of key berry traits viz. anthocyanins and sugars. To test the concept, we used data from Cabernet Sauvignon grown in a hot environment of South Australia. Sources of variation in berry traits included water supply, fruit load, seasonal conditions and their interactions. Anthocyanins and sugars were measured in berry samples taken 7–8 times between veraison and harvest. Rates and durations of accumulation of anthocyanins and sugars per berry were derived from a bi‐linear model between amount of compound and thermal time. We develop a framework based on ‘α’ a parameter representing the slope of the regression between rate and duration in a log‐log scale. This relationship accommodates three conditions viz. (a) potentially plastic, rate‐driven trait (α–1), (b) potentially plastic, duration‐driven trait (α < –1), and (c) a stable trait, whereby variation in rate and variation in duration cancel each other (α=–1). Under our experimental conditions, amount of anthocyanins (range of variation 148%) was more plastic than amount of sugars per berry (range of variation 37%). The slope α captured the differential plasticity of these traits: α was significantly greater than –1 for anthocyanins and statistically undistinguishable from –1 for sugars. The rate‐dominated accumulation of anthocyanins explained the relatively large variation in this constituent whereas the tightly coupled, inverse relationship between duration and rate (α–1) explained the relative stability of sugars per berry. We conclude that our allometric‐type relationship between rate and duration allows for the quantification of cultivar‐environment specific plasticity of important berry traits.

Effect of water deficit and severe shoot trimming on the composition ofVitis vinifera L. Merlot grapes and wines

“…Higher anthocyanins/sugar ratios were achieved under water deficit conditions (Figure ) as already reported in other red cultivars (Sadras et al. , Sadras and Moran ); DI consistently enhanced anthocyanins accumulation during ripening in both years (Figure a,b, Table ) through a stimulus of their biosynthesis as shown by Castellarin et al. (2007a,b) and a reduction of the berry mass as shown by Roby et al.…”

Effects of irrigation and rootstock onVitis vinifera(L.) cv. Shiraz berry composition and shrivel, and wine composition and wine score

“…(), Sadras et al. () and Kennedy et al. () found reduced irrigation led to smaller berries and higher colour density in the fruit and wine.…”

Modelling variety-dependent dynamics of soluble solids and water in berries ofVitis vinifera

“…Whereas the allometric conditions for increasing concentration of soluble solids and decreasing water concentration follow from the definitions, i.e. the scaling exponent is the ratio of the relative rate of accumulation of soluble solids or water and the relative rate of berry growth (Pearsall 1927, Niklas 1994), the magnitude of the scaling exponents depends on environmental factors (Sadras and McCarthy 2007, Sadras et al. 2007) and may also differ with variety‐dependent traits.…”