Studies On The Change Of Calcium Concentration And Calcium Channel Of Maize's Root Tip Cell Under Osmotic Stress

As a cell the secondary messenger in plant cell, the change of Ca²⁺ concentration directly reflects the cell change situation which is stimulated from the outside. Most study showed that the Ca²⁺ concentration change played an important role during regulating the plant to drought resistant under the osmotic stress. A great deal of research, which were on entire plant and the cell level by pharmacology, indicated that the Ca²⁺ intervened the ABA signal transduction process, but it was only the indirect experiment. The direct evidence only come from Ca²⁺ localization distribution and the change of Ca²⁺ concentration and the character of calcium-channel type. Therefore, the change of Ca²⁺ concentration by confocal and the calcium channel type by the patch-clam technique under the osmotic stress were studied for the purpose of further verifying the function of Ca²⁺ in the signal transduction process, also for further study the function of Ca²⁺ messenger. Combination of the calcium channel character and the physiological reaction of cell under the osmotic stress, had the vital significance in regarding the further expounding calcium signal function.In the paper, maize root was selected as material.The protoplast was firstly prepared and dyed with FDA, its vigor was very high. On the basis, the free Ca²⁺ flurescene intensity were observed and the Ca²⁺concentrations were measured after treated with PEG and ABA by Confocal. The result showed that: the free Ca²⁺ dynamic changed and the Ca²⁺ concentration changed after 10min (after treated), those indicated that Ca²⁺ participated in the ABA transduction process in root system under osotic stress.For further proving the the origin of cytosolic Ca²⁺, EGTA, Vp and FTP were used in the experiment separately.The result showed that EGTA and Vp obviously suppressed Ca²⁺ concentration increasing which was induced by ABA in the root tip cell. This indicated that the cytosolic free Ca²⁺ by ABA inducing came from extrocellular majoritly while treatments, but also little came from the release of calcium pool. CaM inhibitor-TFP could cause the Ca²⁺ fluorescence intensity to change as a way of fluctuateing, this indicated CaM perhaps participated in the root system arid signal ABA transmission process.Simultaneously, through recording the calcium electric current by the whole-cell mode, we discovered that: with the increase of Ca²⁺ electricity current, the time of calcium channel opening hour was obviously bring forward. It indicated that PEG perhaps promote Ca²⁺ flow-in through activateing the calcium channel. It is belong to voltage-dependent, hyperpolarization-activated, Ca²⁺-permeable, inward-recitified conductance which existed in plasma membrane of maize root tip cell.