Haploid induction through ovary culture in cucumber

Haploidization technique is the modern and advanced breeding technique used to enhance economically essential crops, including cucumber, to meet consumers’ preferences and needs worldwide. This study aimed to evaluate the effects of factors such as genotype, thermal pre-treatments, and nutrient medium combinations that are considered in haploid production via ovary culture in four commercial cucumber varieties. Four different induction media with four distinct maturation medium combinations and three F1 and one open-pollinated (Beith Alpha) cucumber varieties were used. All explants (cucumber ovaries’ slices) were inoculated in induction media and remained at 35 °C/3 d in the dark, then were transferred at 25 ± 1 °C 16-/8-h light/dark photoperiod for a further 9 d. The results of the study demonstrated that the embryo-like structure (ELS) formation rate was high in induction medium 2 which was successful in all varieties of Ptk40 (20%), Botanik (20%), Beith Alpha (16%), and Sardes (13.3%), respectively, compared to other induction medium combinations used in this study. Callus formation rates obtained from regeneration of medium 2 supplemented with 2.0 mg L⁻¹ 6-benzylaminopurine (BAP) and 0.5 mg L⁻¹ 1-naphthaleneacetic acid (NAA) were Ptk40 (65%), Sardes (60%), and Botanik (40%), and no callus was formed in Beith Alpha. Due to the findings of this study, the nutrient medium containing KIN and 2,4-D seems to be successful during induction of haploid embryo formation in cucumbers. One plantlet germinated but perished at early stage. The plantlet regeneration was observed to be low. Further studies are required to optimize the embryo regeneration medium composition due to the cucumber growing seasons, genotypes, and nutrient medium.