title: The calcium-dependent protein kinase HvCDPK1 mediates the gibberellic acid response of the barley aleurone through regulation of vacuolar function.
abstract: In the aleurone cells of the cereal grain, gibberellic acid (GA) induces the secretion of hydrolases that mobilize endosperm reserves to fuel early seedling growth. GA is known to trigger a range of cellular responses, including increases in cytoplasmic calcium, vacuolar reserve mobilization, gene transcription, and the synthesis and secretion of hydrolases. To further define elements of the Ca2+-dependent GA response machinery, we have cloned a Ca2+-dependent protein kinase (HvCDPK1) from these cells. Although expression of an inactivated (D140N) version of this kinase did not affect GA-induced gene expression or changes in cytosolic Ca2+, it did inhibit secretion, cell vacuolation, and vacuolar acidification, all responses linked to the GA response. Additionally, recombinant wild-type HvCDPK1 activated the V-type H(+)-ATPase present in isolated aleurone vacuoles. These results suggest HvCDPK1 may mediate Ca2+-dependent events of the GA response, such as control of vacuolar function, that lie downstream of transcriptional regulation.
authors.affiliation: School of Biological Sciences and Center for Reproductive Biology, Washington State University, PO Box 644236, Pullman, WA 99164, USA.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: McCubbin
authors.forename: Sian M
authors.initials: SM
authors.lastname: Ritchie
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Swanson
authors.forename: Simon
authors.initials: S
authors.lastname: Gilroy
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D003600:Cytosol / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000494:pharmacology*; D001467:Hordeum / Q000166:cytology / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000235:genetics; D015398:Signal Transduction; D014158:Transcription, Genetic; D014617:Vacuoles / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D000251:Adenosine Triphosphatases; D002118:Calcium; D005875:Gibberellins; D011494:Protein Kinases; D011994:Recombinant Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C007842:gibberellic acid