ВЛИЯНИЕ ЗАСОЛЕНИЯ НА РОСТ И РАЗВИТИЕ БЕРЁЗЫ ПУШИСТОЙ И КАРЕЛЬСКОЙ БЕРЁЗЫ В УСЛОВИЯХ IN VITRO И EX VITRO
Authors: Табацкая Т.М. , Внукова Н.И. , Машкина О.С. 
Published: February 2025

Изучено влияние засоления NaCl в условиях in vitro и ex vitro на рост и развитие коллекционных клонов B. pubescens и B. pendula var. сarelica различных режимов хранения in vitro (стандартные условия культивирования и при пониженной положительной температуре). Выявлена сходная реакция на солевой стресс у растений берёзы в условиях in vitro (NaCl 0,2 %, 3 месяца) и ex vitro (4 г NaCl на 1кг субстрата, 1 месяц). В обоих случаях наблюдалось снижение регенерационных (активность побегообразования) и ростовых (линейный рост побега и накопление биомассы) показателей, уровень которых зависел от генотипических (в большей степени видовых) особенностей исходного материала и режимов его хранения, что следует учитывать при проведении исследований по селекции in vitro.

Introduction. In vitro simulation of stress is one of the promising trends of plant breeding for resistance to negative environmental factors (including salination). Birch is one of highly valuable forest-forming species in Russia. It is suitable for protective afforestation where salt-tolerant and drought-resistant species are required. The goal of the study was to evaluate the effect of long-term growing of collectors` birch clones on their growth and development under simulated salinity stress (NaCl) both in vitro and ex vitro. No such research has been conducted on birch so far. Research objects and methods. Authors used microplants of 4 clones of white birch (Betula pubescens) and Karelian birch (Betula pendula Roth var. carelica) from in vitro collection. The collection was preserved in two modes for many years: I mode — normal (standard) cultivation conditions, with a temperature of 25±2°С, a photoperiod consisting of 16 hours of light and 8 hours of darkness, and light intensity of 2.0 klx; II mode – with a low positive temperature (4±1°С), low light intensity (0.5 klx) and a shortened photoperiod consisting of 6 hours of light and 18 hours of darkness. In both modes authors used 1/2MS hormone-free nutrient medium. Microshoots grown under those two modes of conservation were subjected to salination in vitro (NaCl, 0.2%, for 3 months) and ex vitro (4g of NaCl per 1 kg of substrate, for 1 month). Than, authors evaluated the regeneration activity (the intensity of shoot formation in vitro), relative values of height, and biomass of plants in vitro and ex vitro. Results. The study has demonstrated the decrease in the regeneration activity, growth rate and biomass accumulation under salinity conditions both in vitro and ex vitro. The response of birch clones to the NaCl inhibitory effect depends on the genotypic characteristics (for the most part, depending on the species) of the source material and its in vitro storage mode. The clones of white birch showed the highest resistance to salinity, which could be due to their polyploid nature (2n= 56). Under the same NaCl salinity stress conditions both in vitro and ex vitro the clones of white birch showed the best results with the I storage mode (demonstrated by the lowest depression of growth and biomass accumulation in relation to the control), whereas the Karelian birch clones performed better with II storage mode. Conclusion. The birch plants responded to the salinity stress under in vitro and ex vitro conditions in a similar way. In both cases, their regeneration and growth decreased, the extent of the decrease depended on the genotypic characteristics (for the most part, depending on the species) of the source material and its in vitro storage modes, which should be taken into account when conducting in vitro breeding researches. To increase the efficiency of selection of white birch stable genotypes, it is preferable to use I in vitro storage mode, and for the Karelian birch – II storage mode.