In vitro induction of callusogenesis in soryz

Purpose. Select the composition of the nutrient medium and explants for in vitro inducing the callogenesis in soryz. Methods. The objects were 10 varieties of soryz: ‘Helios’, ‘Saliut’, ‘Tytan’, ‘Merkurii’, ‘Odeskyi 302’, ‘Evropa’, ‘Kvarts’, ‘Samaran 6’, ‘Oktan’, ‘Fakel’. For the induction of callusogenesis, explants grown in vitro culture were selected, specifically leaves of shoots and apical parts of the root. Solid nutrient medium with agar-agar (7–8 g/l) was modified according to Murasige-Skoog (MS), Schenk-Hildebrandt (SH) and Hamburg-Eveleg (B5). To initiate callusogenesis, the nutrient medium was supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6‑benzylaminopurine (BAP) in concentrations from 0.2 to 2.0 mg/l. Results. For all types of nutrient media, concentrations of 2,4-D of 0.4 and 0.6% were the optimal for the induction of callusogenesis. At these concentrations, 17% and 20% of callus from leaf blades and 24% and 30% from the apical parts of the root were obtained in MS nutrient medium. Lower indicators were noted for the use of SH nutrient medium: 15% and 18% in leaves and 20% and 27% in roots. The lowest percentage of induction on medium B5 was 13% and 16% and 18% and 25% by types of explants, respectively. An increase in the concentration of 2,4-D to 0.8 mg/l led to a decrease in the induction of callus mass compared to the addition of 0.4 mg/l: leaf plates – from 12% to 15%, roots – from 15% to 22%. In particular, at the studied concentrations (1.0–1.6 mg/l) on MS medium, callus was obtained in 9–12% of leaf explants and 11–17% of root explants. Analyzing the data, it is advisable to note the advantage of the nutrient medium MS, with the use of which varieties obtained from 18 to 28% of callusogenesis frequency from leaf blades. The lowest percentage of induction was found in the case of using the B5 medium: ‘Samaran 6’ – 21%, ‘Evropa’ – 20%, ‘Quartz’ – 18%, ‘Tytan’ – 17 and ‘Merkurii’ – 16%. The lowest percentage was in the varieties ‘Odeskyi 302’ and ‘Helios’ – 14%, ‘Oktan’ – 13% and ‘Saliut’ – 11%. Conclusions. Regardless of the concentration of 2,4-D in the nutrient medium on a hormone-free basis, induction of callusogenesis occurred more intensively in roots compared to leaves. At a concentration of 0.2 mg/l, callus formation was from 5 to 10% in leaves, and from 10 to 14% in the apical parts of the root in all studied nutrient media. Among the studied varieties, a significant advantage was noted in the variety ‘Fakel’, in which callus induction was at the level of 22–37% in different media. In MS medium, the highest rates of callusogenesis were obtained in the varieties ‘Samaran 6’, ‘Evropa’ and ‘Tytan’ (31–35%), and the lowest by ‘Saliut’, ‘Kvarts’ and ‘Helios’ (21–24%).