Production of Hypo- and Hyper-tetraploid Seedlings from Open-, Self-, and Cross-pollinated Hypo- and Hyper-tetraploid Grape

Seedless grape (Vitis spp.) cultivars with large berries can be developed from hypo-and hypertetraploid seedlings. The low occurrence of hypo-and hypertetraploid seedlings, however, has impeded the breeding of new hypo-and hypertetraploid grape varieties. In order to establish hypo- and hypertetraploid seedlings, we examined the chromosome numbers in seedlings of self-, open-, and cross-pollinated hypotetraploid 'Takao' and hypertetraploid 'RB9127K' grape. Three of the five seedlings (60%) from 'Takao' were aneuploid, including one with 74 chromosomes (2n=4x-2) and two with 75 chromosomes (2n=4x-1). In 'RB9127K', 26 of the 193 seedlings (13.5%) were aneuploid, including three seedlings with 75 chromosomes (2n=4x-1), 18 with 77 chromosomes (2n=4x+1), and five with 78 chromosomes (2n=4x+2). The high frequency of aneuploids from 'Takao' and 'RB9127K' grape indicates that meiosis in hypo-and hypertetraploid female parents is prone to segregation error. These results suggest that various hypo-or hypertetraploid seedlings can be successfully produced using hypo-or hypertetraploid grapes as female parents, which can contribute to the development of new seedless grape varieties with large berries.