低温锻炼与CaCl2处理对毛白杨幼苗可溶性总蛋白、CaM及抗冻性的影响

低温锻炼提高了毛白杨幼苗叶片和枝条中钙调素 (CaM)和可溶性总蛋白含量 ,同时也提高了幼苗的抗冻性 .CaCl2 处理对上述低温锻炼的作用有加强的效果 ,体现在明显提高了CaM和可溶性总蛋白含量以及幼苗抗冻性 ;钙离子螯合剂EGTA、钙离子通道阻断剂LaCl3 或钙调素拮抗剂CPZ处理则减弱了低温锻炼的效应 ,表现出CaM和可溶性总蛋白含量以及幼苗抗冻性明显降低 .进一步研究发现 ,CaCl2 处理的低温锻炼不仅能减轻低温胁迫引起的CaM和可溶性总蛋白含量的下降程度 ,而且有利于幼苗在恢复过程中CaM和可溶性总蛋白水平的迅速回升 .这表明Ca2 + CaM可能参与了CaM和可溶性总蛋白的合成及抗冻性的诱导

Effects of Cold Acclimation and CaCl2 on Total Soluble Protein,CaM and Freezing Resistance of Populus tomentosa Seedlings

Populus tomentosa seedlings used for cold acclimation at - 3℃ were pretreated with or without 10 mmol@ L- 1 CaCl2, 3 mmol@ L- 1 of Ca2 + chelator EGTA, 0.1 mmol- L- 1 of Ca2 + channel inhibitor LaCl3, and 0.05 mmol@ L- 1 of CaM antagonist CPZ. The changes in the contents of total soluble protein and CaM, and freezing resistance in all pretreated seedlings in various periods ( viz: following cold acclimation, chilling stress and recovery) were investigated. Results showed that cold acclimation increased the contents of total soluble protein and CaM, and freezing resistance of seedlings, which could be strongly reduced by the pretreatments of EGTA CPZ and LaCl3. Cold acclimation combined with CaCl2 pretreatment enhanced the effect of cold acclimation on freezing resistance, and obviously increased the contents of total soluble protein and CaM, reduced the declining degree of the contents of total soluble protein and CaM caused by chilling stress as compared with cold acclimation, augmented the increase in the level of total soluble protein and CaM during the recovery periods. Further analysis found that an increase in total soluble protein content during cold acclimation with or without CaCl2 pretreatment mainly resulted from the increase in content of heat-stable protein in total soluble protein. It is suggested that Ca2+ -calmodulin may be involved in the synthesis of total soluble protein, and the induction of freezing resistance of seedlings.