Home – Home – Jornals – Siberian Journal of Forest Science 2018 number 4

An efficient system for the in vitro propagation of the endangered medicinal and winter-hardy ornamental plant, Rhododendron mucronulatum Turcz., through high frequency shoot induction from seedlings and in vitro -derived apical shoots was developed. While testing different zeatin (Z) concentrations in the seedling culture, both axillary shoot regeneration and adventitious shoot formation on hypocotyls were observed. The highest frequency of shoot regeneration from seedlings (80 %), including formation of adventitious buds on hypocotyls (25 %), was recorded in the presence of 1.0 µM Z. The highest adventitious shoot numbers per explant (31.12 ± 6.19) were formed under 2.5 µM Z. Histological examination confirmed that adventitious buds directly originated from parenchymal cells of the hypocotyl. The effect of different concentrations of 2-isopentenyladenine and Z alone as well as in combination with indole-3-acetic acid (IAA) on axillary shoot proliferation from apical shoot explants was studied. The highest regeneration frequency (100 %) and shoot multiplication (9.70 ± 0.63) with a maximum length (15.75 mm) were obtained by using a combination of 0.1 µM IAA with 1.0 µM Z. The most efficient root formation was achieved through 4-hour pulse treatment with 148.0 µM indole-3-butyric acid followed by ex vitro rooting in a mixture of peat and sand (1 : 1). This study contributes to conventional and genetic-engineering breeding programs for creating new frost-resistant cultivars and developing a strategy for R. mucronulatum germplasm conservation, as well as commercial large-scale propagation.