[Effects of germanium on cell growth, polysaccharide production and cellular redox status in suspension cultures of protocorm-like bodies of Dendrobium huoshanense].

To solve the problem of low growth rate and metabolism level in suspension cultures of protocorm-like bodies (PLBs) of Dendrobium huoshanense. The effects of germanium on PLB proliferation and accumulation of polysaccharides together with nutrient utilization were investigated and the contents of reducing sugars, soluble proteins, the activities of antioxidant enzymes and redox status of the cells of PLB were analyzed. The results indicated that the optimum concentration of germanium dioxide (4.0 mg/L) significantly enhanced the cell growth and accumulation of polysaccharides, greatly improved contents of reducing sugars and soluble proteins, increased the activities of superoxide dismutase (SOD) and catalase (CAT) but decreased the activity of peroxidase(POD). The cell dry weight and production of polysaccharides were 32.6 g/L and 3.78 g/L, respectively. The analysis of cellular redox status showed that the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in cells and the activity of glutathione reductase were significantly increased by the addition of germanium dioxide. The suitable concentration of germanium dioxide was beneficial to the cell growth and the accumulation of polysaccharides.