Evaluation of table grape genetic resources for sugar, organic acid, and amino acid composition of berries

Abstract

Variations in the sugar, organic acid, and amino acid composition of table grape berries were determined in three successive years in 129 grape cultivars. Three regional groups were represented among these cultivars; European, North American, and Japanese. All cultivars are conserved at the Fukuoka Agricultural Research Center in Japan. Three representative ripe average-sized bunches were selected from one vine per cultivar. Ripeness was judged by visual observation of seed color change to dark brown, without senescence of berry tissue. Soluble solids content (SSC) was weakly correlated with other berry traits, but strongly correlated with total sugar content. Genotypic variance (r g 2 ) was significant for all berry traits, especially for a ratio (sugar composition) and c ratio (amino acid composition). The yearly effect (r y 2 ) was significant for SSC, total sugar content, and total amino acid content but not for a ratio, titratable acidity, b ratio (organic acid composition) and c ratio. Repeatabilities over the 3 years were very high for a ratio and c ratio, while they were low for SSC, total sugar content, titratable acidity, b ratio, and amino acid content. Correlation coefficients between the values of each individual year and the 3-year mean were relatively high for the a ratio and c ratio. We highlight the varietal differences in the a ratio and c ratio because of the low environmental variation. Two types of grape were distinguished on the basis of sugar composition: hexose accumulators (a ratio C 0.81) and sucrose accumulators (a ratio B 0.80). The hexose-and sucrose-accumulating traits were related to genetic or regional differences. Cultivars were classified into five types on the basis of the c ratio. Like the a ratio, variation in the c ratio is closely related to cultivar parentage and regional differences. Vitis vinifera cultivars exhibited a skewed distribution with a c ratio below 1.0 because they contain low levels of sweet amino acids. In contrast, the c ratio frequently exceeded 1.5 in American hybrid cultivars because they contain high levels of sweet amino acids.

Characterization of Sugars and Organic Acids in Commercial Varieties of Table Grapes

“…At harvest, the total sugars account for more than 90% of TSS, measured by a refractometer. This result confirms the importance of using this parameter as a sugar content indicator and a harvesting index (Shiraishi et al, 2010). However, our results suggest that in earlier stages of development (H-4 or earlier), there are other soluble compounds, such as organic acids, that affect the TSS.…”

“…In addition to the four basic flavors (sweet, sour, salty, and bitter) that humans can recognize in fruits and vegetables, aroma has an important influence on the final consumer acceptance of the commodity (Defilippi et al, 2009). Among the flavor metabolites already mentioned, sugar and organic acid compositions, which are measured through total soluble solids (TSS) and titratable acidity (TA), are most commonly associated with the taste of fruits, including table grapes (Ferguson and Boyd, 2002;Shiraishi et al, 2010).…”

Ecophysiological, Genetic, and Molecular Causes of Variation in Grape Berry Weight and Composition: A Review

“…No significant year effect was detected on TSS of 14 Vitis species (paired t-test, p = 0.11) by reevaluating the results from Kliewer (1967a). Although the year effect on TSS was reported as significant in a study dealing with 129 grape cultivars among three years, its contribution of variance to total variance of TSS was only 1.5% (Shiraishi et al 2010).…”

“…Sugars accumulated in berry originate from sucrose that is imported from photosynthesizing leaves (Hale andWeaver 1962, Swansom andElshishiny 1958). Sugar composition in grape berry is mainly determined by genotype (Liu et al 2006, Shiraishi 2000, Shiraishi et al 2010, while sugar concentration varies with berry development (Coombe 1992), environment, and viticulture practices (Clingeleffer 2010, Jackson and Lombard 1993, Kliewer and Dokoozlian 2005, Reynolds and Vanden Heuvel 2009). …”

“…Among 26 species of Vitis including species from North America and Middle East regions, Kliewer (1967a) reported a wider range of variation in TSS at maturity, ranging from 13.7 Brix (V. champini) to 31.5 Brix (V. riparia from Wyoming). Among different sugars, all the reported V. vinifera cultivars accumulate predominantly glucose and fructose (each range from 46 to 164 g/L) with very low traces of sucrose (Hawker et al 1976, Liu et al 2006, Shiraishi et al 2010. In contrast, V. labrusca and V. rotundifolia cultivars and interspecific hybrids produced with these species are consistently characterized by the accumulation of non-negligible levels of sucrose (from 5 to 58.28 g/L), together with moderate amounts of glucose and fructose (from 35 to 54 g/L) (Carroll et al 1971, Carroll and Marcy 1982, Liu et al 2006, Shiraishi 2000, Shiraishi et al 2010.…”