Seedless-Seedless Grape Hybridization via In-Ovulo Embryo Culture

Abstract

The effect of berry sampling time and genotypic difference in stenospermocarpic seedless grapes on the recovery of viable embryos through in ovulo embryo culture was examined. In 5 open-pollinated seedless cultivars, berry weight increased consistently as the fruit developed, but the ovule length did not correspondingly increase, being either constant or shrinking. The recovery rate of viable embryos significantly increased as the days after anthesis proceeded, especially on the 40th day. During the culture, polyembryony was occasionally observed in some ovules. At the micropylar end of the ovule, most multiple embryos emerged adventitously from the hypocotyl-root axis of zygotic embryo. In 5 open-pollinated selections and 6 cultivars, veraison ranged from 49 to 66 days after anthesis. Varietal difference in the recovery of viable embryos from ovules sampled at veraison was significant, ranging from 0 to 24.7%. In a total of 20 crosses between seedless accessions, the recovery rate of viable embryos significantly varied from 2.7 to 47.0%. The rate of plant recovery in vitro ranged from 0.6 to 24.9%. F₁ progenies produced through in ovulo embryo culture in seedless x seedless crosses segregated as follows ; completely seedless : perceptible seed traces : seeded=24 : 56 : 21.