Doubled haploid production of sunflower (Helianthus annuus L.) through irradiated pollen-induced parthenogenesis

Induced parthenogenesis as a possible method of haploidization in sunflower (H. annuus L.) was tested in previous investigations (Todorova et al., 1994) and conditions for reproducible regeneration of gynogenic doubled haploids were established by the present work. Forty eight treatments were studied, involving four pollen donors and four recipient hybrids. Pollen was irradiated with doses of 300 Gy, 600 Gy and 900 Gy. In total, 2279 embryos were cultivated in vitro of which 1107 plants were obtained and 582 of them produced seeds after selfing. The ploidy level of the regenerants was evaluated at the two – three leaf stage and 296 of the plantlets obtained were haploids. Some of them underwent spontaneous diploidization, the others were treated with colchicine solution for chromosome doubling. The diploid plantlets were checked for their gynogenic origin by genetical and biochemical methods. The effectiveness of the method expressed as the number of agronomically useful DH lines to the number obtained that were fertile and resistant to downy mildew, branched and unbranched plants was 8,6% on average. This revised version was published online in July 2006 with corrections to the Cover Date.