Production of doubled haploid plants in cucumber (Cucumis sativus L.) via parthenogenesis

Double haploid production methods have great potential for accelerating breeding programs for cultivar development. Parthenogenesis, an embryo arising from unfertilized egg cells, is the most efficient technique for Cucumis sativus L. breeding programs. This study focused on the creation of haploid plants in cucumbers through the fertilization of female flowers with gamma radiation–treated pollen. The anthers were treated with different doses of gamma rays (200.0, 300.0, and 500.0 Gray). Pollen viability and vigor were investigated using the TTC (2,3,5-triphenyl tetrazolium chloride) and germination tests, respectively. Isolated female flowers were pollinated with irradiation-affected pollen. According to the results, pollination is most effective in producing haploid offspring when pollen has been exposed to radiation at a dose of 300.0 Gy. The ploidy levels of the regenerated plantlets were determined and confirmed using flow cytometry. In most plants, 78.39% were found to have only half the normal number of chromosomes (haploid), and 21.6% had a mix of normal and half chromosomes (mixoploid). The number of chromosomes in haploid plants was doubled by in vitro treatment of nodal explants with different colchicine concentrations. The use of 500.0 mg L−1 colchicine for 24 h led to the most successful regeneration rate of doubled haploid cells at 85.4%. The optimized double haploid production protocol would be applicable for producing 100% homozygous lines for utilization in breeding programs.