title: The Arabidopsis cax3 mutants display altered salt tolerance, pH sensitivity and reduced plasma membrane H+-ATPase activity.
abstract: Perturbing CAX1, an Arabidopsis vacuolar H+/Ca2+ antiporter, and the related vacuolar transporter CAX3, has been previously shown to cause severe growth defects; however, the specific function of CAX3 has remained elusive. Here, we describe plant phenotypes that are shared among cax1 and cax3 including an increased sensitivity to both abscisic acid (ABA) and sugar during germination, and an increased tolerance to ethylene during early seedling development. We have also identified phenotypes unique to cax3, namely salt, lithium and low pH sensitivity. We used biochemical measurements to ascribe these cax3 sensitivities to a reduction in vacuolar H+/Ca2+ transport during salt stress and decreased plasma membrane H+-ATPase activity. These findings catalog an array of CAX phenotypes and assign a specific role for CAX3 in response to salt tolerance.
authors.affiliation: United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Bronwyn J
authors.initials: BJ
authors.lastname: Barkla
authors.forename: Joy
authors.initials: J
authors.lastname: Marshall
authors.forename: Jon K
authors.initials: JK
authors.lastname: Pittman
authors.forename: Kendal D
authors.initials: KD
authors.lastname: Hirschi
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000222:Adaptation, Physiological; D017920:Antiporters / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D018525:Germination / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D018021:Lithium Chloride / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D054712:Salinity; D036226:Seedlings / Q000254:growth & development; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
chemical_list: D017920:Antiporters; D029681:Arabidopsis Proteins; C506406:CAX3 protein, Arabidopsis; D027682:Cation Transport Proteins; D005030:Ethylenes; D010937:Plant Growth Regulators; C027614:calcium-hydrogen antiporters; D012965:Sodium Chloride; D013395:Sucrose; D000040:Abscisic Acid; C036216:ethylene; D012964:Sodium; D006180:Proton-Translocating ATPases; D018021:Lithium Chloride; D002118:Calcium