Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China.It can survive severe environmental stress including high salinity in its natural habitat.Thus,we investigated the involvement of anti-oxidative enzymes,photosynthetic pigments and flavonoid metabolism in the adaptation of R.soongorica to saline environments.R.soongorica was treated with 0,100,200 and 400 mM NaCl solutions for 14 days.Soil salt content increased significantly by watering with high content of NaCl solution,and no variation between 8 and 14 days during treatment.The levels of peroxidation of lipid membranes(measured by malondialdehyde content)and the activities of three antioxidant enzymes(superoxide dismutase(SOD),peroxidase(POD)and ascorbate peroxidase(APX))increased under salt stress.Chlorophyll and carotenoid content decreased with increasing salt content.The ratio of Chl a/Chl b and carotenoid/Chl exhibited significant increase under 400 mM NaCl.However,total flavonoid and anthocyanin contents and key enzyme activities in the flavonoid pathway including phenylalanine ammonialyase(PAL)and Chalcone isomerase(CHI)decreased under salt stress.These findings possibly suggest that R.soongorica has an adaptation protection mechanism against salt-induced oxidative damage by inducing the activity of antioxidant enzymes and maintaining a steady level of carotenoid/Chl.
