title: Arabidopsis sodium dependent and independent phenotypes triggered by H⁺-PPase up-regulation are SOS1 dependent.
abstract: Coordinate regulation of transporters at both the plasma membrane and vacuole contribute to plant cell's ability to adapt to a changing environment and play a key role in the maintenance of the chemiosmotic circuits required for cellular growth. The plasma membrane (PM) Na⁺/H⁺ antiporter (SOS1) is involved in salt tolerance, presumably in sodium extrusion; the vacuolar type I H⁺-PPase AVP1 is involved in vacuolar sodium sequestration, but its overexpression has also been shown to alter the abundance and activity of the PM H⁺-ATPase. Here we investigate the relationship between these transporters utilizing loss-of-function mutants of SOS1 (sos1) and increased expression of AVP1 (AVP1OX). Heightened expression of AVP1 enhances pyrophosphate-dependent proton pump activity, salt tolerance, ion vacuolar sequestration, K⁺ uptake capacity, root hair development, osmotic responses, and PM ATPase hydrolytic and proton pumping activities. In sos1 lines overexpressing AVP1, these phenotypes are negatively affected demonstrating that sos1 is epistatic to AVP1. Enhanced AVP1 protein levels require SOS1 and this regulation appears to be post-translational.
authors.affiliation: Department of Genome Sciences, University of Washington, S410 Foege Building South, 1705 NE Pacific Street, Seattle, WA 98195, USA.
authors.forename: Soledad F
authors.initials: SF
authors.lastname: Undurraga
authors.forename: Mirella P
authors.initials: MP
authors.lastname: Santos
authors.forename: Julio
authors.initials: J
authors.lastname: Paez-Valencia
authors.forename: Haibing
authors.initials: H
authors.lastname: Yang
authors.forename: Peter K
authors.initials: PK
authors.lastname: Hepler
authors.forename: Arnoldo R
authors.initials: AR
authors.lastname: Facanha
authors.forename: Kendal D
authors.initials: KD
authors.lastname: Hirschi
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Gaxiola
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004843:Epistasis, Genetic; D015151:Immunoblotting; D043564:Inorganic Pyrophosphatase / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D055049:Salt Tolerance / Q000235:genetics / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; C477653:SOS1 protein, Arabidopsis; D017923:Sodium-Hydrogen Exchangers; C505048:AVP1 protein, Arabidopsis; D043564:Inorganic Pyrophosphatase