Preliminary genetic analysis of sucrose accumulation in berries of table grapes

Abstract

Based on the results of HPLC analysis of sugar composition of grape berries, table grape populations were classified into two types: those that accumulate hexoses with trace amounts of sucrose [hexoses accumulator, HA], and those that accumulate significant quantities of sucrose in addition to hexoses [sucrose accumulator, SA]. To study the genetic control of sugar composition, we examined five types of seedling populations: [HA]×[HA] (166 F1 of Vitis vinifera); [HA]×[HA] (366 F1 of Vitis labruscana×V. vinifera); [HA]×[SA] (139 F1 of V. labruscana×V. vinifera); [SA]×[HA] (25 F1 of V. labruscana×V. vinifera); and [SA]×[SA] (53 F2 of V. labruscana×V. vinifera). The segregation patterns among seedling populations suggested that the trait of sucrose accumulation in grape berries might be recessively inherited. There was no difference between diploid and tetraploid grapes in terms of the segregation pattern of sugar composition. Based on the segregation patterns in F1 and F2 seedling populations, we proposed a monogenic control model for the trait of sucrose accumulation in grape berries. If the single-gene hypothesis is correct, complete dominance of hexoses accumulation [A] over sucrose accumulation [a] could explain the observed segregation patterns of diploids: [HA] (presumed genotype, AA and Aa); [SA] (presumed genotype, aa). For tetraploids, the presumed genotype of [HA] would be homozygous (AAAA) or heterozygous (AAAa, AAaa, Aaaa), and that of [SA] would be homozygous (aaaa).