Arabidopsis CBL10Interacts With CIPK11and Regulates The Plasma Membrane H~+-ATPase Activity

CBL-CEPK pathway, as an important Ca2+signaling system, plays a key role in plant response to abiotic stresses such as salt, low K+and high pH etc. Under suboptimal conditions, CBL and CIPK first form CBL-CIPK complexes, and then regulate the expressions of some downstream genes, finally response to environmental stresses. As seen from previous studies, CBL-CIPK signaling system can improve the tolerance of the plant to abiotic stresses by regulating the transports of sodium ion, potassium ion and so on, but the relationship between CBL-CIPK pathway and H+transport is not clear.Plasma membrane (PM) vesicles were isolated using aqueous two-phase partitioning method from the leaves of wild-type (WT) and AtCBL10mutant (cbl10) Arabidopsis plants and used to study the effect of CBL10on PM H+-ATPase activity. The results showed that PM H+-ATPase activity of cbl10mutant plants was significantly lower than that of wild-type plants. It is reported that Arabidopsis CIPK11(AtCIPKll) could negatively regulate the activity of PM H+-ATPase. AtCBL10could also regulate the PM H+-ATPase activity in the present work. Normally, CBL and CIPK pathways regulate the physiological processes in the form CBL-CIPK complexes in plants. So we think that the regulation of AtCBL10on PM H+-ATPase may be involved in AtCIPKl1.We constructed yeast two-hybrid vectors of AtCBL10and AtCIPK11, the results from yeast two hybrid system showed that AtCBL10could interact with AtCIPK11. Analysis of the pull-down experiment also proved the interaction between AtCBL10and AtCIPK11in vitro. Cbl10mutants could grow better compared to wild type plants under alkaline environment (pH7.7and pH8.1), further indicating that AtCBL10may positively regulate PM H+-ATPase activity to control the pH homeostasis in plants. The cbl10mutant exposed NaCl or LiCl treatments grew significantly slower than wild type plants did under normal and alkaline conditions; both KC1and CaCl2treatments inhibited the growths of cbl10mutant and wild type plants compared to normal condition, but there was no difference between the growths of cbl10mutant and wild type plants treated with KC1or CaCl2. In summary, AtCBL10may interact with AtCIPKll to form CBL10-CIPK11protein kinase complex in plants, and the complex regulates the activity of PM H+-ATPase in plants grown in suboptimal environments.