Abstract

The effects of three polysaccharides; exopolysaccharide, water-extracted mycelial polysacharide, and sodium hydroxide-extracted mycelial polysaccharide (EPS, WPS and SPS) and their corresponding oligosaccharides; oligosaccharide obtained by hydrolysis of EPS, oligosaccharide obtained by hydrolysis of WPS and oligosaccharide obtained by hydrolysis of SPS (EOS, WOS and SOS) as the elicitors prepared from endophytic fungus Berkleasmium sp. Dzf12 on growth and diosgenin accumulation in cell and seedling cultures of Dioscorea zingiberensis were investigated. Among all the elicitation treatments, EOS generated the most satisfactory effect on enhancing diosgenin production in both cell and seedling cultures. The highest diosgenin yield (2.89 mg/L) in the cell cultures treated with EOS at 20 mg/L was achieved, which was 6.88-fold of control (0.42 mg/L). Meanwhile, when the seedlings were treated with EOS at 40 mg/L, the maximum diosgenin yield (14.68 mg/L) was achieved, which was 4.60-fold as the control (3.19 mg/L). Oligosaccharides WOS and SOS also showed obvious effects on enhancing diosgenin accumulation in the cell and seedling cultures, which were stronger than their corresponding polysaccharides WPS and SPS. The diosgenin yield in the cell cultures separately treated with WOS at 40 mg/L or SOS at 20 mg/L reached the maximum, which were 4.27- and 2.86-fold of control, respectively. For the seedlings treated with WOS or SOS, the maximum diosgenin yield was 8.43 mg/L, which was 2.64-fold of control. The results indicate that the polysaccharides and oligosaccharides as the elicitors from Berkleasmium sp. Dzf12 could be applied in D. zingibereneis cell and seedling cultures to produce diosgenin.

Key words: Polysaccharide, oligosaccharide, endophytic fungus, Berkleasmium sp. Dzf12, Dioscorea zingiberensis, diosgenin accumulation, cell cultures, seedling cultures.

Abbreviation

EPS, Exopolysaccharide; WPS, water-extracted mycelial polysaccharide;SPS, sodium hydroxide-extracted mycelial polysaccharide; EOS, oligosaccharide obtained by hydrolysis of EPS; WOS, oligosaccharide obtained by hydrolysis of WPS;SOS, oligosaccharide obtained by hydrolysis of SPS; dw, dry weight; Dzf12, endophytic fungus Berkleasmium sp. Dzf12.