Relevance. Doubled haploids (DH-plants) are excellent material for genetic research and breeding due to their complete homozygosity. The genus Raphanus from the Brassicaceae family is the toughest to produce doubled haploid plants through isolated microspore culture in vitro (IMC). The study of the causes of disturbed root formation and the development of elements of this stage of technology will significantly increase the effectiveness of the IMC technology for European radish.Methods. The study included three varieties from the collection of the Federal State Budgetary Scientific Institution Federal Scientific Vegetable Center (FSBSI FSVC): Teplichny Gribovsky, Rozovo-krasniy s belim konchikom and Rhodes. The experiments used a standard protocol for obtaining DH plants using IMC technology in a standard form and with a modification of the rooting stage. The solid MS medium (with agar 7g/L): MS without hormones, MS medium supplemented with IAA at concentrations of 0.5; 1 and 2 mg / L and liquid MSm medium supplemented with 0.1 mg / L kinetin were used for rooting of regenerated plants. All media were supplemented with 20 g/L sucrose. We used three types of techniques for transplanting plant explants onto a solid hormonefree MS medium: planting micro-shoots with their basal part immersed by 2-3 mm into the medium; planting in a well made in a nutrient medium using tweezers under sterile conditions; and landing on the surface of the medium without embedment.Results. In this work, we studied the features of the stage of rooting of regenerated European radish plants in vitro conditions. The transplant technique has been proven to be important for the successful establishment of radish micro-shoots. Plant explants must be planted strictly on the surface of a solid hormone-free nutrient medium MS, without embedment. The use of tubes with bridges made of filter paper and MSm liquid medium with the addition of 0.1 mg/L kinetin for the induction of root formation also showed high efficiency. For plants prone to the formation of root-like structures (RLS) with secondary tumors (ST), multiple dissection of abnormal formations with successive transplants is necessary. Modification at the rooting stage of micro-shoots growing has increased the percentage of successfully adapted DH plants in vivo conditions from 0-14% to 95-98%.

The line fixers of sterility from the other pairs with genotype TsitNrfrf are encouraged to use for off-patent biological copyright protection paternal pollinating lines. In this case, the F1 hybrids will always have a TsitSrfrf genotype and will be sterile, which makes it impossible to obtain F2 progeny.