Abstract:

The effect of drought stress on the activity of protective enzymes and oxidative damage in Nostoc flagelliforme
suspension cells was investigated. The mechanism for the ameliorative effect of exogenous silicon on the cellular damage was
explored to provide a theoretical basis for alleviating drought stress. Artificial cultivation of Nostoc flagelliforme suspension
cells was conducted under 15 g/100 mL polyethylene glycol (PEG-6000) simulated drought stress. The effect of Si (sodium
silicate) at different concentrations (0.2, 0.4, 0.8, 1.2 mmol/L and 2.0 mmol/L) on protective enzyme activities and the contents
of proline and soluble sugar in Nostoc flagelliforme suspension cells was investigated. The best alleviative effect on droughtinduced
damage was observed upon treatment with 0.4 mmol/L Si. At this concentration, the activities of protective enzymes
(including SOD and POD) and the contents of proline and soluble sugar were significantly increased, while malondialdehyde
(MDA) content and electrolyte leakage were significantly decreased. These results indicate that dosage effect of Si (as sodium
silicate) existed on the alleviation of drought stress in Nostoc flagelliforme suspension cells, and the best alleviative effect on
drought-induced damage was 0.4 mmol/L Si, which elevated the drought tolerance of Nostoc flagelliforme suspension cells.

Key words: drought stress, Si, Nostoc flagelliforme suspension cells, protective enzyme activities, proline