Optimization of technology steps for obtaining white cabbage DH-plants.

White cabbage is one of the economically important crops among the representatives of the genus Brassica L. To create highly productive F1 hybrids with improved characteristics, the breeders need genetically diverse breeding material, which takes a long time to produce. It is possible to significantly accelerate this stage of breeding by obtaining doubled haploids (DH-plants). The lack of standardized, efficient and reproducible protocols for in vitro cultivation of different plant species, covering several factors and their interactions, often hinders the practical implementation of the method. Plant material, cultivation conditions and composition of nutrient media are determinants of embryogenesis efficiency. As a result of this study, the protocol for obtaining doubled haploids in in vitro culture of isolated microspores was optimized for late maturing white cabbage. The optimal bud size for introduction into in vitro culture varied from 3.5 to 5.0 mm. For the studied genotypes, the combined effect of high-temperature stress at 32 °C for 48 h and pH 5.8 stimulated the highest embryoid yield. The use of 3.5 g/L phytogel as a gelling agent was not effective. The use of flow cytometry allowed for separation of doubled haploids (69.8 %) from haploids (8.4 %), triploids (1.5 %) and tetraploids (20.3 %) at an early stage of development. Molecular genetic analysis with polymorphic microsatellite loci (SSR-analysis) confirmed the haploid origin of the diploid regenerant plants.