Preliminary Studies On Freezing Resistance Of Pteroceltis Tatarinowii

To explore the physiological and biochemical mechanism of Pteroceltis tatarinowii during low temperature stress, the changes in contents of H2O2, MDA , membrane permeability redox status, activities of some key enzymes involving in the ascorbate-glutathione cycle, pentose phosphate pathway (OPPP), glycolysis and Calvin cycle were studied in isolated twigs and seedlings leaf of P. tatarinowii. The major results were summarized as follows:LT50 of isolated twigs and seedlings leaf of P. tatarinowii is -6.63 ℃ and -4.97 ℃ ,that shows P. tatarinowii has weaker freezing resistance.To P. tatarinowii, SOD,POD, CAT, APX, MDAR, DHAR, G6PDH, PFK, HK,NADPH,NADH,ASA, GSH and reducing sugar all are primary guide lines to denote freezing resistance and Pro and soluble protein are not key fators.In this experiment , the higher activities of superoxide dismutase (SOD), peroxides(POD), Catalase(CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH), hexokinase (HK) and phospho-fructokinase (PFK), and the more contents of reduced ascorbate (ASA), reduced glutathione (GSH), NADH, NADPH were observed during the beginning of freezing acclimation. After low temprature destroys the membrane structure, the lower activities of enzymes that had been mentioned and the less contents of ASA,GSH, NADH, NADPH were observed.