IMPROVEMENT OF THE CHRYSANTHEMUM × KOREANUM HORT. CLONAL MICROPROPAGATION PROCESSES USING BACILLUS MEGATERIUM ONU500

The aim of this study was to improve the Chrysanthemum × Koreanum micropropagation processes using Bacillus megaterium ONU500 at the post-aseptic adaptation stage. Methods. At the initial stages of clonal micropropagation, two surface sterilization protocols with different fungicidal preparations were tested. The influence of the agar concentration in the medium on the development of explants was determined. At the ex vitro adaptation stage, the roots of the microclones were inoculated with bacteria of the strain B. megaterium ONU500. Results. The most effective protocol for plant material surface disinfection, which included quinozol and ethanol, was established. It was determined that the use of Murashige and Skoog (MS) nutrient medium supplemented with 0.4% agar at the stage of in vitro culture establishment increased the survival of chrysanthemum initial explants by 9.3% and accelerated proliferation by 1 day. It was found that inoculation of the chrysanthemum microclone rhizosphere with bacteria had a positive effect on the growth of adapted plantlets, increasing their survival rate by 20.4–22.2%, shoot height by 1.8–1.9 cm, and average number of nodes by 2.0–2.2 nodes. Conclusion. The effectiveness of the use of fungicides for the treatment of chrysanthemum plant material during in vitro culture establishment and the influence of the consistency of the nutrient medium on the development of explants were determined, which is new and relevant for increasing the efficiency of clonal micropropagation of this plant. Also, experiments on the inoculation of chrysanthemum microclones at the stage of ex vitro adaptation were carried out for the first time, and the positive effect of such inoculation on the morphometric characteristics of seedlings and their survival rate was shown. When establishing chrysanthemum explants in vitro, it is recommended to use the fungicide quinozol for surface sterilization, and carry out cultivation in a semi-liquid nutrient medium with 0.4% agar. At the postaseptic adaptation stage of microclones, it is advisable to inoculate the roots with bacteria of the strain B. megaterium ONU500 at concentrations of 108–109 CFU/ml.