Cellular Mechanism Of The Extracellular Ca²⁺ Induced Cytosolic Ca²⁺ Rise In Arobidopsis Roots

Calcium is an essential nutrient for growth and development of the plant, and widely participates in cell signaling pathways as secondary massager. Progresses have been made in the methodology to study the variation in cytosolic calcium, which greatly enhanced our understanding of the calcium signaling cascades. But, how Ca2+ entries into the cells and the impact of the external environment should be studied furtherly. In this study, Arabidopsis expressing an aequorin (AEQ) was used to detect effects of extracellular environment on calcium absorption of Arabidopsis root cells.Firstly, different concentration of CaCl2 and GdCl3 was used as stimuli. Consistently, two different ions induced dose-dependent increasing of intracellular Ca2+. Similar to animal cells, the following desensitization of CaCl2 and cross desensitization experiment of CaCl2 and GdCl3 suggested that Ca sensor receptor would exist on cell membrane. Pharmacology experiments analysis showed that cAMP, IP3 and ion type glutamate receptors (GLRs) participated in the extracellular Ca2+ induced intracellular cytosolic Ca ([Ca]cyt) changes. Besides, effects of environment changes on [Ca2+]cyt, including K+, whereas Mg2+, NaCl, H2O2 and pH were also determined. K+can promote plant uptake of Ca2+, Mg2+, NaCl, H2O2 inhibit [Ca2+]cyt increasing, and increased [H+]ext will partially inhibits the increasing of [Ca2+]cyt.This experiment takes a preliminary study of plants to absorb Caz+ and analyses the influence factors. In addition, this study proved that receptors involved in the regulation of the extracellular Ca2+ induced [Ca2+]cyt rise in Arabidopsis roots.