Biotechnology of obtaining garden strawberry regenerate plants ex vitro using silicon chelates from renewable plant raw materials

One of the problems of insufficient cultivation of garden strawberries in the Novosibirsk region is the lack of industrial production of high-quality planting material, on which the crop yield directly depends. The technology of clonal micropropagation can help to solve the problem of obtaining genetically identical healthy planting material of high quality. The efficiency of clonal micropropagation largely depends on the optimization of the cultivation stages. Adaptive responses of garden strawberry regenerants (‘Solnechnaya Polyanka’, ‘Alpha’) during rooting and ex vitro acclimation under the influence of an environmentally friendly silicon-containing mechanocomposite made from renewable plant materials were studied. To stimulate rhizogenesis in microshoots the following treatments were used: watering with an aqueous solution of Murashige-Skoog nutrient medium containing ¼ concentration of standard medium components; pulse treatment with an aqueous solution of 30 mg/l indoleacetic acid (for 4 hours) followed by watering with a solution of ¼ Murashige-Skoog; a single watering with a solution of ¼ Murashige-Skoog with the addition of 0.3, 1.0, 3.0 g/l of mechanocomposite; dry dipping the basal part of the microshoots with a mechanocomposite followed by watering with a solution of ¼ Murashige-Skoog. It was found, that dry dipping the basal part of the microshoots with a mechanocomposite is the most effective treatment method of regenerants in ex vitro conditions. This treatment significantly increased the frequency of rhizogenesis (up to 95% versus 25-45% in the control), stimulated the development of the root system (the length of the roots increased relative to the control by 2.5-4.3 times, the number of roots per plant by 1.2-2.0 times, the dry weight of the roots by 3.0 times for the cv. ‘Alpha’) and the above-ground system of plants (the area of the leaf blade increased by 1.2-2.0 times, the dry weight of the shoots by 2.6-3.7 times), increased the content of the main photosynthetic pigments in the leaves of the regenerants (the content of chlorophyll a + b increased by 1.2 times, carotenoids by 1.2-1.4 times). Under the influence of the mechanocomposite, the leaves of the regenerants acquired signs of a xeromorphic organization. An increase in the density of stomata on the abaxial side of the leaf in the cv. ‘Alpha’ (by 1.4 times), intensive accumulation of epicuticular waxes on the lower epidermis of the leaf blades of the regenerants of two cultivars was noted. It was determined that silicon accumulates in the aboveground part of the garden strawberry regenerants. The minimum silicon content was in the control (2020 μg/g), under the influence of the mechanocomposite, the silicon content increased (up to 3500 μg/g with watering and 3200 μg/g with dusting with the mechanocomposite). The developed technology allows to eliminate the in vitro rooting stage and reduce the overall clonal micropropagation cycle by 4 weeks, ensuring high quality of garden strawberry planting material.