Obtaining Triploid Muscat Grapes by in vitro Culture of Ovules and Embryos After Crossing Between Diploid and Tetraploid Cultivars

To breed new seedless grape cultivars we crossed 'Muscat of Alexandria' (2x) and its 4x mutant reciprocally and cultured the immature ovules and embryos in vitro. Ovules sampled 50 days after crossing could develop embryos on a liquid medium of half strength of MS supplemented with 2 ppm of IAA, 0.4 ppm of GA3 and 0.1 % of activated charcoal. After 55 days culture, normally developed embryos were obtained from 20 to 30 % of the ovules from 4x×2x and 50 to 70 % of those from 2x×4x. Embryos taken out from the cultured ovules were planted on an agar medium of MS or N&N for 55 to 65 days. Ten to twenty % of embryos from 2x×4x crossing grew to rooted plantlets successfully. They were proved to be triploid after the measurement of chromosome number. Embryos from 4x×x2x, however, could not grow to plantlets because of the failure of rooting.