NUTRIENT MEDIUM MODIFICATION FOR PROPAGATING TEA MICROSHOOTS (CAMELLIA SINENSIS (L.) O. KUNTZE) IN VITRO

During the cultivation of tea microshoots in vitro, numerous problems arise related to phenolic exudation of explants, microbial contamination of tissues and nutrient medium, as well as related to decrease in morphogenic potential due to a lack or excess of growth regulators. Microshoots of ‘Colkhida’ tea have been in the in vitro collection at FRC SSC of RAS for a long time. To maintain their growth and development in the active phase of morphogenesis, many nutrient medium protocols were modified, concerning both their composition and concentration of the main growth regulators. This study provides new data on the nutrient medium modification, with amendments, regarding the concentration of the base salts composition for tea, as well as growth regulators – 6-BAP and gibberellic acid GA3 ; their effect on the multiplication process of tea microshoots in vitro was studied. In the first block of studies, a nutrient medium with a set of salts according to the Murashige-Skoog, with the addition of 6-BAP (2.0–5.0 mg/l) was used. It was found that the concentration of 6-BAP had a significant effect on the number of tea microshoots obtained from one explant. Thus, the majority of microshoots (5.6 pcs.) were observed in the variant with a concentration of 6-BAP – 4.0 mg/l, while in the control this indicator was only 2.2 pcs. In the variant with an increased concentration of 6-BAP to 5.0 mg/l, an active increase in callus was noted, which led to growth inhibition. In the second block of studies, the MS medium was increased by 1.5 times in terms of the basic composition of salts, and in addition to 6-BAP (2.0–5.0 mg/l) it was supplemented with gibberellic acid GA3 (1.0–2.5 mg/l). Modification of the nutrient medium associated with an increase in its salts composition by 1.5 times, as well as the use of different combinations and concentrations of 6-BAP (2.0–3.0–4.0 mg/l) and gibberellic acid (1.0–1.5–2.0 mg/l) allowed to increase the number of tea microshoots from 1 explant to 6.8–7.8–8.9 pcs, respectively