A calcium sensor and its interacting protein kinase are global regulators of abscisic acid signaling in Arabidopsis.
The phytohormone abscisic acid (ABA) triggers an oscillation in the cytosolic Ca(2+) concentration, which is then perceived by unknown Ca(2+) binding proteins to initiate a series of signaling cascades that control many physiological processes, including adaptation to environmental stress. We report here that a Ca(2+) binding protein, SCaBP5, and its interacting protein kinase, PKS3, function as global regulators of ABA responses. Arabidopsis mutants with silenced SCaBP5 or PKS3 are hypersensitive to ABA in seed germination, seedling growth, stomatal closing, and gene expression. PKS3 physically interacts with the 2C-type protein phosphatase ABI2 (ABA-insensitive 2) and to a lesser extent with the homologous ABI1 (ABA-insensitive 1) protein. Thus, SCaBP5 and PKS3 are part of a calcium-responsive negative regulatory loop controlling ABA sensitivity.
Department of Plant Sciences, University of Arizona, Tucson 85721, USA.
Yan
Y
Guo
Liming
L
Xiong
Chun-Peng
CP
Song
Deming
D
Gong
Ursula
U
Halfter
Jian-Kang
JK
Zhu
D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D009154:Mutation / Q000187:drug effects / Q000502:physiology; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018514:Plant Structures / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism
D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; D010940:Plant Proteins; C112941:SOS3 protein, Arabidopsis; D000040:Abscisic Acid; D011494:Protein Kinases; C087434:ABI1 protein, Arabidopsis; C106443:ABI2 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases; D002118:Calcium