title: A PIIB-type Ca2+-ATPase is essential for stress adaptation in Physcomitrella patens.
abstract: Transient cytosolic Ca(2+) ([Ca(2+)](cyt)) elevations are early events in plant signaling pathways including those related to abiotic stress. The restoration of [Ca(2+)](cyt) to prestimulus levels involves ATP-driven Ca(2+) pumps, but direct evidence for an essential role of a plant Ca(2+)-ATPase in abiotic stress adaptation is missing. Here, we report on a stress-responsive Ca(2+)-ATPase gene (PCA1) from the moss Physcomitrella patens. Functional analysis of PCA1 in a Ca(2+) transport-deficient yeast mutant suggests that PCA1 encodes a P(IIB)-type Ca(2+)-ATPase harboring an N-terminal autoinhibitory domain. In vivo localizations identified membranes of small vacuoles as the integration site for a PCA1:GFP fusion protein. PCA1 mRNA levels are up-regulated by dehydration, NaCl, and abscisic acid, and PCA1 loss-of-function mutants (DeltaPCA1) exhibit an enhanced susceptibility to salt stress. The DeltaPCA1 lines show sustained elevated [Ca(2+)](cyt) in response to salt treatment in contrast to WT that shows transient Ca(2+) elevations, indicating a direct role for PCA1 in the restoration of prestimulus [Ca(2+)](cyt). The altered Ca(2+) response of the DeltaPCA1 mutant lines correlates with altered expression levels of stress-induced genes, suggesting disturbance of a stress-associated signaling pathway. We propose that PCA1 is an essential component for abiotic stress adaptation in Physcomitrella involved in the generation of a specific salt-induced Ca(2+) signature.
authors.affiliation: Plant Biotechnology, Institute of Biology II, Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
authors.forename: Enas
authors.initials: E
authors.lastname: Qudeimat
authors.forename: Alexander M C
authors.initials: AM
authors.lastname: Faltusz
authors.forename: Glen
authors.initials: G
authors.lastname: Wheeler
authors.forename: Daniel
authors.initials: D
authors.lastname: Lang
authors.forename: Hauke
authors.initials: H
authors.lastname: Holtorf
authors.forename: Colin
authors.initials: C
authors.lastname: Brownlee
authors.forename: Ralf
authors.initials: R
authors.lastname: Reski
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Frank
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D019068:Bryopsida / Q000201:enzymology* / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000235:genetics* / Q000378:metabolism*; D003890:Desiccation; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009997:Osmotic Pressure; D030821:Plants, Genetically Modified; D012441:Saccharomyces cerevisiae; D055049:Salt Tolerance / Q000502:physiology; D012492:Salts / Q000494:pharmacology; D013312:Stress, Physiological / Q000502:physiology*; D014617:Vacuoles / Q000201:enzymology
chemical_list: D012492:Salts; D000040:Abscisic Acid; D000252:Calcium-Transporting ATPases; D002118:Calcium