钙-钙调素对中东杨扦插苗的诱导抗冻作用

以零下低温锻炼和结合效应剂（CaCl2、钙离子螯合剂EGTA、钙离子通道阻断剂LaCl3或钙调素拮抗剂CPE）处理的低温锻炼下的中东扬扦插苗为试材，对其体内丙二醛（MDA）及钙调素CaM含量，SOD、POD及线粒体Ca^2-＋ATPase活性分别进行测定。结果表明，低温锻炼不仅在一定程度下提高了幼苗CaM含量，提高了SOD、POD和Ca^2＋-ATPase活性，降低了MDA含量；而且减少了低温胁迫所引起的SOD、POD，Ca^2＋＋ATPase和CaM含量的下降程度以及MDA的增加幅度。在低温锻炼的同时。用CaCl2处理能加强低温锻炼的效果，但这种效应可被EGTA、LaCl3或CPZ处理抑制。经低温锻炼后，幼苗中的CaM含量的增加有助于SOD、POD和线粒体Ca^2＋-ATPase活性的提高，进而对幼苗抗冻性的提高有明显的促进作用。

The role of calcium and calmodulin in freezing-induced freezing resistance of Populus davidiensis cuttings

Low temperature signal in woody plants,Populus davidiensis cuttings after being treated with CaCl_2,Ca~(2+) chelator EGTA,Ca~(2+) channel inhibitor LaCl_3 or CaM antagonist CPZ were used for freezing acclimation.The changes in the CaM and MDA contents,the activities of SOD,POD and Ca~(2+)-ATPase of cuttings were investigated.The results showed that freezing acclimation not only increased the CaM content,the activities of SOD,POD and Ca~(2+)-ATPase of cuttings,and decreased the MDA content as compare with control cuttings.but also reduced the degree of decline in CaM content,and in SOD,POD and Ca~(2+)-ATPase activities caused by freezing stress and enhanced the level of increase in CaM content.Treatment with CaCl_2 at the time of freezing acclimation enhanced the effect of freezing acclimation on the above-mentioned indexes.but this enhancement was abolished by EGTA,LaCl_3 or CaM antagonist CPZ.The increase of CaM content that promote the higher of activities of SOD,POD and Ca~(2+)-ATPase of cuttings,and further result in the adaptive changes associated with the development and enhancement of freezing resistance.