title: Anion channel SLAH3 functions in nitrate-dependent alleviation of ammonium toxicity in Arabidopsis.
abstract: Slow anion channels (SLAC/SLAH) are efflux channels previously shown to be critical for stomatal regulation. However, detailed analysis using the β-glucuronidase reporter gene showed that members of the SLAC/SLAH gene family are predominantly expressed in roots, in addition to stomatal guard cells, implicating distinct function(s) of SLAC/SLAH in the roots. Comprehensive mutant analyses of all slac/slah mutants indicated that slah3 plants showed a greater growth defect than wild-type plants when ammonium was supplied as the sole nitrogen source. Ammonium toxicity was mimicked by acidic pH in nitrogen-free external medium, suggesting that medium acidification by ammonium-fed plants may underlie ammonium toxicity. Interestingly, such toxicity was more severe in slah3 mutants and, particularly in wild-type plants, was alleviated by supplementing the media with micromolar levels of nitrate. These data thus provide evidence that SLAH3, a nitrate efflux channel, plays a role in nitrate-dependent alleviation of ammonium toxicity in plants.
authors.affiliation: College of Life Sciences, Sichuan University, Chengdu, 610064, China; Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA, 73072, USA; NJU-NJFU Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing, 210093, China.
authors.forename: Xiaojiang
authors.initials: X
authors.lastname: Zheng
authors.forename: Kai
authors.initials: K
authors.lastname: He
authors.forename: Thomas
authors.initials: T
authors.lastname: Kleist
authors.forename: Fang
authors.initials: F
authors.lastname: Chen
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
mesh_terms: D064751:Ammonium Compounds / Q000633:toxicity*; D000838:Anions / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009566:Nitrates / Q000378:metabolism*; D018517:Plant Roots
chemical_list: D064751:Ammonium Compounds; D000838:Anions; D029681:Arabidopsis Proteins; D007473:Ion Channels; D009566:Nitrates; C582432:SLAH3 protein, Arabidopsis
keywords: growth; nitrogen; nutrients