Optimization of explants in vitro sterilization protocol of some deciduous tree species

Abstract

One of the methods of obtaining planting material of deciduous plants, in particular common ash (Fraxinus excelsior L.), broad-leaved linden (Tilia platyphyllos Scop.) and silver birch (Betula pendula Roth) is microclonal propagation. Asepticity of explants is a prerequisite for microclonal plant propagation. Chemical sterilization with liquid substances is mostly used for this purpose. The mode of decontamination is influenced by a number of factors, in particular the genotype of the plant. The purpose of the study was to optimize the sterilization protocol of F. excelsior, T. platyphyllos and B. pendula explants for microclonal propagation. For research, 20–30 cm of shoots isolated from 12-year-old T. platyphyllos, 10-year-old B. pendula, and 15-year-old F. excelsior in February-March 2021 were used. Plant material was cultured according to conventional methods on a nutrient medium MS (Murashige & Skoog, 1962). Biotechnological methods were used (plant tissue culture in vitro, microclonal propagation). MS Excel software package was used to process the experimental data, the mean and its standard error were calculated. One-way analysis of variance (ANOVA) was performed to analyze the effect of explant sterilization on asepsis. The expediency of keeping plant material during the day in 0.1 % solution of «Samshit»  F. excelsior and 0.3 % solution «Fundazole»  T. platyphyllos and B. pendula is shown. The sterilization protocol of experimental plants (efficiency over 50 %) was optimized by using a stepwise method using 70 % ethyl alcohol, 1.0 % and 2.0 % AgNO3 and 2.5 % and 5.0 % NaClO. The effect of the sterilization regime of experimental plants on asepsis is statistically significant at the level of 5%. To initiate the explants, a culture medium according to the MS prescription was used with the addition of 0.25 mg/L kinetin and 2.0 g/L activated carbon. Further studies are aimed at developing a protocol for direct regeneration of microshoots of F. excelsior, T. platyphyllos and B. pendula under the action of components of the culture medium in vitro.