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Plant Physiol. 2015 Mar;167(3):1039-57. doi: 10.1104/pp.114.249870. Epub 2015 Jan 22.

Two distinct families of protein kinases are required for plant growth under high external Mg2+ concentrations in Arabidopsis.

Author information

1
Laboratories of Plant Molecular Physiology (J. Mo., T.Y., Y.T., K.M., S.K., J.Mi., K.Y.-S.) andPlant Nutrition and Fertilizers (T.F., S.N.), Graduate School of Agricultural and Life Sciences andBiotechnology Research Center (S.Y., T.I.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan;Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305-8686, Japan (Y.F.);Laboratory of Plant Stress Biology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8577, Japan (Y.F.); andRIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (H.N., Y.N., F.T., K.S.).
2
Laboratories of Plant Molecular Physiology (J. Mo., T.Y., Y.T., K.M., S.K., J.Mi., K.Y.-S.) andPlant Nutrition and Fertilizers (T.F., S.N.), Graduate School of Agricultural and Life Sciences andBiotechnology Research Center (S.Y., T.I.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan;Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305-8686, Japan (Y.F.);Laboratory of Plant Stress Biology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8577, Japan (Y.F.); andRIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (H.N., Y.N., F.T., K.S.) akys@mail.ecc.u-tokyo.ac.jp.

Abstract

Protein phosphorylation events play key roles in maintaining cellular ion homeostasis in higher plants, and the regulatory roles of these events in Na(+) and K(+) transport have been studied extensively. However, the regulatory mechanisms governing Mg(2+) transport and homeostasis in higher plants remain poorly understood, despite the vital roles of Mg(2+) in cellular function. A member of subclass III sucrose nonfermenting-1-related protein kinase2 (SnRK2), SRK2D/SnRK2.2, functions as a key positive regulator of abscisic acid (ABA)-mediated signaling in response to water deficit stresses in Arabidopsis (Arabidopsis thaliana). Here, we used immunoprecipitation coupled with liquid chromatography-tandem mass spectrometry analyses to identify Calcineurin B-like-interacting protein kinase26 (CIPK26) as a novel protein that physically interacts with SRK2D. In addition to CIPK26, three additional CIPKs (CIPK3, CIPK9, and CIPK23) can physically interact with SRK2D in planta. The srk2d/e/i triple mutant lacking all three members of subclass III SnRK2 and the cipk26/3/9/23 quadruple mutant lacking CIPK26, CIPK3, CIPK9, and CIPK23 showed reduced shoot growth under high external Mg(2+) concentrations. Similarly, several ABA biosynthesis-deficient mutants, including aba2-1, were susceptible to high external Mg(2+) concentrations. Taken together, our findings provided genetic evidence that SRK2D/E/I and CIPK26/3/9/23 are required for plant growth under high external Mg(2+) concentrations in Arabidopsis. Furthermore, we showed that ABA, a key molecule in water deficit stress signaling, also serves as a signaling molecule in plant growth under high external Mg(2+) concentrations. These results suggested that SRK2D/E/I- and CIPK26/3/9/23-mediated phosphorylation signaling pathways maintain cellular Mg(2+) homeostasis.

PMID:
25614064
PMCID:
PMC4348753
DOI:
10.1104/pp.114.249870
[Indexed for MEDLINE]
Free PMC Article

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