Male flower induction significantly affects androgenesis in cucumber (Cucumis sativus L.)

Male flower induction and androgenesis in three genotypes of cucumber (Cucumis sativus), two Beth alpha F1 hybrids (BT1 and BT2, gynoecious) and Dastgerdi (DTG, monoecious), were evaluated. Induction of male flowers in gynoecious cucumber cultivars was assessed by single and combinatorial spraying of AgNO3 (3 mM), GA(3) (1.5 mM) and CoCl2 (3 mM) after the first true leaf emergence. After 6 weeks from the beginning of treatments, the average numbers of male flowers induced by spraying AgNO3, GA(3), and CoCl2 were 42, 14.5, and 0, respectively. Androgenesis was performed in two gynoecious cultivars, in which the donor plants were treated with AgNO3 (3 mM) or GA(3) (1.5 mM) and the DTG cultivar without treatment. Among the three cultivars, the DTG showed the highest percentage of embryogenic calli formation (62.2%) and number of embryos per anther (1.81). In the gynoecious cultivars, the percentage of embryogenic calli formation (27.1%) and number of embryos per anther (0.23) in the anthers of GA(3) treated plants were significantly higher than those treated by AgNO3. Cytological and SSR marker analysis of regenerants showed that 16 plants were spontaneous doubled haploid, 2 plants were diploid and one plant was tetraploid.