In vitro DIRECT SHOOT REGENERATION FROM Rhodiola rosea L. LEAF EXPLANTS

Wild plant species are of great interest as a source of pharmacologically valuable compounds but a great number of them are endemic and/or endangered ones. Modern plant biotechnology can provide reliable methods for their utilization without disturbing natural populations. In vitro culture methods for Rhodiola species are being intensively developed to include them into various biotechnological programmes. Aim. Development of a protocol for direct Rhodiola rosea L. plant regeneration from leaf explants. Methods. The leaves of R. rosea aseptically growing plants were used as the explants. Several variants of Murashige and Skoog (1962) agar-solidified culture medium supplemented with different combinations of auxins (1-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D)) and cytokinins (kinetin and 6-benzylaminopurine (BAP)) were estimated as potential regeneration-inducing media. Regeneration frequency was calculated as the percentage of leaves that produced shoots. Results. The use of MS medium supplemented with 2.5 mg/l BAP and 1.0 mg/l 2,4-D allowed inducing shoot formation with 100% frequency. An increase in the 2,4-D content up to 2.5 mg/l and decrease in BAP content to 1.0 mg/l resulted in decreasing of the regeneration frequency to 62.5%. Regeneration frequency was 25% and 62%, respectively, on the media containing 1.0 mg/l kinetin + 2.5 mg/l 2,4-D and 2.5 mg/l kinetin + 1.0 mg/l 2,4-D. Conclusions. R. rosea leaf explants have demonstrated high regeneration capacity with using the studied combinations of plant growth regulators. MS medium supplemented with 2.5 mg/l BAP and 1.0 mg/l 2,4-D allowed inducing shoot regeneration in leaf explants with the frequency of 100%. The frequency of regeneration was lower in the case of substitution of BAP for kinetin. The other types of morphogenesis (formation of adventitious roots and/or callus) were also observed.