Turczaninowia (Dec 2018)
Clonal micropropagation of Astragalus sericeocanus Gontsch. and content of phenolic compounds in vitro
Abstract
In vitro propagation system for Astragalus sericeocanus Gontsch., an endemic species of the coast of Lake Baikal, was developed for the first time. This species is a source of valuable secondary metabolites with medicinal properties. The efficiency of mechanical and chemical scarifications for overcoming physical dormancy of seeds of this species was estimated. The highest percentage of seed germination (80.7 ± 0.88 %) at the minimum duration of germination (7.3 ± 0.33 days) was obtained by mechanical treatment. The effect of thidiazuron (TDZ; 0.05–2.0 mg/l) supplemented to B5 medium on regenerative potential of different explant types was studied. Efficient TDZ concentrations induced direct organogenesis from primary shoots of seedlings (regeneration frequency up to 100 %) and axillary buds of microshoots (up 31.1 %) were revealed. The results showed that 0.1 mg/l TDZ was the ptimal concentration for the development of axillary meristems of primary shoots. Following cultivation of microshoots on the medium for propagation supplemented with 0.2 mg/l TDZ resulted in formation of 11.4 ± 0.64 shoots per explant. Callus formation was observed on medium supplemented with 1.0 and 0.05 mg/l TDZ using hypocotyl and cotyledon explants. Analysis of secondary metabolites by high performance liquid chromatography (HPLC) showed that the composition and content of phenolic compounds in regenerants obtained on medium supplemented with 0.05–0.1 mg/l TDZ were comparable to in vivo plants, indicating high biosynthetic capacity of microplants. Quercetin, kaempferol, apigenin and izorhamnetin were identified in the hydrolysates of extracts of in vivo plant leaves. Hydrolysates of in vitro plants extracts were characterized by the absence of apigenin only.
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