title: Arabidopsis glutamate receptor homolog3.5 modulates cytosolic Ca2+ level to counteract effect of abscisic acid in seed germination.
abstract: Seed germination is a critical step in a plant's life cycle that allows successful propagation and is therefore strictly controlled by endogenous and environmental signals. However, the molecular mechanisms underlying germination control remain elusive. Here, we report that the Arabidopsis (Arabidopsis thaliana) glutamate receptor homolog3.5 (AtGLR3.5) is predominantly expressed in germinating seeds and increases cytosolic Ca2+ concentration that counteracts the effect of abscisic acid (ABA) to promote germination. Repression of AtGLR3.5 impairs cytosolic Ca2+ concentration elevation, significantly delays germination, and enhances ABA sensitivity in seeds, whereas overexpression of AtGLR3.5 results in earlier germination and reduced seed sensitivity to ABA. Furthermore, we show that Ca2+ suppresses the expression of ABSCISIC ACID INSENSITIVE4 (ABI4), a key transcription factor involved in ABA response in seeds, and that ABI4 plays a fundamental role in modulation of Ca2+-dependent germination. Taken together, our results provide molecular genetic evidence that AtGLR3.5-mediated Ca2+ influx stimulates seed germination by antagonizing the inhibitory effects of ABA through suppression of ABI4. These findings establish, to our knowledge, a new and pivotal role of the plant glutamate receptor homolog and Ca2+ signaling in germination control and uncover the orchestrated modulation of the AtGLR3.5-mediated Ca2+ signal and ABA signaling via ABI4 to fine-tune the crucial developmental process, germination, in Arabidopsis.
authors: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (D.K., C.J., A.P., S.K., D.C.); andCenter for Plant Aging Research, Institute for Basic Science, Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea (J.M.K.) ddkong169@163.com jkwak@dgist.ac.kr.
authors: Dongdong
authors: D
authors: Kong
authors: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (D.K., C.J., A.P., S.K., D.C.); andCenter for Plant Aging Research, Institute for Basic Science, Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea (J.M.K.).
authors: Chuanli
authors: C
authors: Ju
authors: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (D.K., C.J., A.P., S.K., D.C.); andCenter for Plant Aging Research, Institute for Basic Science, Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea (J.M.K.).
authors: Aisha
authors: A
authors: Parihar
authors: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (D.K., C.J., A.P., S.K., D.C.); andCenter for Plant Aging Research, Institute for Basic Science, Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea (J.M.K.).
authors: So
authors: S
authors: Kim
authors: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (D.K., C.J., A.P., S.K., D.C.); andCenter for Plant Aging Research, Institute for Basic Science, Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea (J.M.K.).
authors: Daeshik
authors: D
authors: Cho
authors: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (D.K., C.J., A.P., S.K., D.C.); andCenter for Plant Aging Research, Institute for Basic Science, Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea (J.M.K.) ddkong169@163.com jkwak@dgist.ac.kr.
authors: June M
authors: JM
authors: Kwak
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D018525:Germination; D008954:Models, Biological; D009154:Mutation; D010937:Plant Growth Regulators / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D017470:Receptors, Glutamate; D014157:Transcription Factors; C000601589:glutamate receptor 3.5, Arabidopsis; D000040:Abscisic Acid; D002118:Calcium