Physiological Changes in Leaves of Medicago falcata Under Low-Temperature Stress

Low temperature significantly restricts crop yield and quality.Medicago falcata(M.falcata)is a typical legume species that exhibits great capacity of tolerance to low temperature.To understand the low-temperature responses in M.falcata,the electrolyte leakage and lipid peroxidation level,and activities of superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD),and contents of reduced glutathione(GSH),soluble protein,soluble sugar and proline were investigated in low-temperature-stressed M.falcata leaves.The electrolyte leakage and malondialdehyde(MDA)content increased,and could be used to quantify low-temperature damage at cellular level.And then,the significant change of SOD,POD and CAT activities,and GSH content reflected the higher reactive oxygen species(ROS)scavenging capacity in M.falcata.In addition,the significant change of soluble protein,soluble sugar and proline contents helped to maintain osmotic equilibrium,energy supply and protein functions.These nine physiological traits were analyzed by gray relational grade analysis and ranked from the highest to the lowest as follows:electrolyte leakage,GSH,proline,soluble protein,MDA,soluble sugar,SOD,CAT and POD,and illustrated that the electrolyte leakage level,GSH and proline contents should be selected and measured priority in M.falcata low-temperature tolerance to improve measurement efficiency.