Effect of mixed salt stress on MDA，protein and antioxidant enzymes of Leymus chinensis in three leaf colors

Aims The mixed salts stress was common in the nature. Salt stress always affect the growth of plant. Different plant species has different adaptive capacity to salty soil. Leymus chinensis is an herbaceous plant with differnt leaf colors. But there few research was conducted to explore the different tolerance and adaptive mechanism to salt stress among  Leymus chinensis in three  leaf colors (grey green, transitional color, yellow green). This study can give us a better understanding in the intra-species adaption on mixed salt soil. Methods Pot experiments for Leymus chinensis in three leaf colors were conducted  under mixed salt treatment in 2010. Malondialdehyde (MDA) content, protein content, and activity of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase(APX), glutathione reductase(GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase(MDHAR), were determined and compared among three leaf colors. Results Content of MDA, protein, and the activity of antioxidant enzymes showed increasing trend with increasing pH in almost all three leaf colors, and all of them come to a head when the salt stress and pH were highest. Moreover, antioxidant enzymes were the highest in grey-green leaf color, and the lowest in yellow green leaf color under the same pH treatment. Conclusions The results suggested that all three leaf colors of Leymus chinensis were tolerant to salt stress and the salt-tolerant was declined according to the order of grey green, transitional color, and yellow green of Leymus chinensis. Grey green leaf color has the highest adaptive ability on salt stress than transitional leaf color and yellow green leaf color. Yellow green leaf color has the weakest adaptive ability on salt stress.