Induction of doubled haploids in sweet cherry (Prunus avium L.)

We report, for the first time, the regeneration of four homozygous lines in sweet cherry ( Prunus avium L.) by in situ parthenogenesis followed by embryo and cotyledon culture. The sweet cherry cultivar 'Altenburger' was pollinated with marked pollen irradiated by gamma-rays at doses ranging from 250 to 1200 Gy. Pollination with such irradiated pollen affected fruit set and the quality of the embryos, and induced the formation of parthenogenic embryos. The immature embryos extracted from the stones, 35 or 75 days after pollination, were cultivated in vitro in an embryo or cotyledon culture. Although flow cytometrical analysis demonstrated the diploid level for all regenerants, four lines could be characterized as homozygous using isoenzyme analysis.