Abstract:

In this study， aseptic plantlets of Glycyrrhiza uralensis generated by tissue culture were used to study the stress effects of NaHCO₃ at 50 mmol· L^-1 with and without exogenous trehalose addition to mitigate stress effects. The biomass， chlorophyll content， concentrations of osmotic regulation substances， antioxidant enzyme activities and total flavonoid contents in the plantlets were monitored. It was found that NaHCO₃-stressed seedlings showed significantly lower biomass， chlorophyll content， concentration of K⁺， total flavonoid contents and antioxidant enzyme （superoxide dismutase， peroxidase， catalase） activities， and significantly higher malondialdehyde （MDA）， proline， soluble sugar and Na⁺ concentrations. Those plantlets treated with 15 mmol·L^{-1trehalose showed significantly improved biomass， chlorophyll content， concentration of K+， total flavonoid content and antioxidant enzyme activities， together with reduced MDA， proline， soluble sugar， and Na+ concentrations. In summary， the application of exogenous trehalose under NaHCO₃ stress had a major beneficial effect on the growth of G. uralensis plantlets and enhanced their alkali-resistance ability of the seedlings. This study provides a theoretical basis for understanding the mechanism of exogenous trehalose enhancement of the alkali-resistance capacity of G. uralensis plantlets.}

Key words: exogenous trehalose, NaHCO₃ stress, Glycyrrhiza uralensis seedlings, osmotic regulation substances, antioxidant enzymes