ABA诱导玉米初生根根尖细胞胞质Ca~(2+)浓度变化

以玉米初生根根尖为材料,在成功制备原生质体的基础上,通过数字共聚焦显微技术,对外源ABA和钙通道试剂处理后玉米根尖细胞胞质Ca2+的荧光及其浓度变化进行了研究。结果显示,10 min内,随着ABA处理时间的延长,Ca2+荧光强度和浓度都增加。表明Ca2+参与了初生根干旱信息的信号传递过程。分别以钙离子螯合剂EGTA、钙通道阻断剂Vp和钙调素拮抗剂TFP与ABA共同处理玉米根部,以进一步探讨Ca2+的来源。结果表明:EGTA和Vp均能显著抑制ABA诱导的根尖细胞胞质Ca2+浓度的增加,说明ABA诱导的初生根根尖细胞胞质Ca2+浓度的增加主要源于胞外,少部分来自于胞内钙库的释放;TFP能使Ca2+荧光产生变化,但浓度上下起伏,表明胞外钙调素也参与了根系干旱信号ABA的信息传递过程,但具体机制有待深入研究。

Changes of Cytosolic Calcium Concentration of Maize Primary Root Tip Induced by ABA

As a secondary messenger in plant cell, Ca~(2+)plays an important role during regulating the plant to drought resistance under osmotic stress. The change of Cytosolic Ca~(2+)concentration directly reflects the cell change which from the extracellular stimulation. In this report,the change of Ca~(2+)fluorescence intensity and concentration of protoplast of Maize primary root tipinduced by ABA were studied by Confocal technology. The protoplast was firstly prepared and high vigor cell was used. Firstly,the Ca~(2+)concentrations were measured after treated with ABA with in10 min. The results showd that the Ca~(2+)concentration increased with the treatment time delay. This indicated that Ca~(2+)participated in the ABA transduction process in primary root tip. For further proving the origin of cytosolic Ca~(2+)after treatments,EGTA,Vp and FTP were added to the ABA solutionin the experiment respectively. The results showed that both EGTA and Vp obviously suppressed Ca~(2+)concentration increasing which wereinduced by ABA in the root tip cell. This indicated that the cytosolic free Ca~(2+)induced by ABA came from extracellular mainly, also little came from the release of cytoplasmic calcium pool. As CaM inhibitor,TFP could change the Ca~(2+)fluorescence intensity and Ca~(2+)concentration when plant were subjected to osmotic stress,this seemed to show that CaM perhaps participated in the process of signal transduction of root system under osmotic stress too, but the mechanism is not known today.