title: Shoot-supplied ammonium targets the root auxin influx carrier AUX1 and inhibits lateral root emergence in Arabidopsis.
abstract: Deposition of ammonium (NH₄+) from the atmosphere is a substantial environmental problem. While toxicity resulting from root exposure to NH₄+ is well studied, little is known about how shoot-supplied ammonium (SSA) affects root growth. In this study, we show that SSA significantly affects lateral root (LR) development. We show that SSA inhibits lateral root primordium (LRP) emergence, but not LRP initiation, resulting in significantly impaired LR number. We show that the inhibition is independent of abscisic acid (ABA) signalling and sucrose uptake in shoots but relates to the auxin response in roots. Expression analyses of an auxin-responsive reporter, DR5:GUS, and direct assays of auxin transport demonstrated that SSA inhibits root acropetal (rootward) auxin transport while not affecting basipetal (shootward) transport or auxin sensitivity of root cells. Mutant analyses indicated that the auxin influx carrier AUX1, but not the auxin efflux carriers PIN-FORMED (PIN)1 or PIN2, is required for this inhibition of LRP emergence and the observed auxin response. We found that AUX1 expression was modulated by SSA in vascular tissues rather than LR cap cells in roots. Taken together, our results suggest that SSA inhibits LRP emergence in Arabidopsis by interfering with AUX1-dependent auxin transport from shoot to root.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Baohai
authors.initials: B
authors.lastname: Li
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Su
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Liming
authors.initials: L
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Guohua
authors.initials: G
authors.lastname: Mi
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Kronzucker
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, ChinaGraduate School of Chinese Academy of Science, Beijing 100081, ChinaDonald Danforth Plant Science Center, St. Louis, Missouri 63132, USAPlant Stress Genomics Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi ArabiaCollege of Resources and Environmental Science, China Agricultural University, Beijing 100094, ChinaDepartment of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Weiming
authors.initials: W
authors.lastname: Shi
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism*; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013395:Sucrose / Q000378:metabolism
chemical_list: C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D000644:Quaternary Ammonium Compounds; D012333:RNA, Messenger; D013395:Sucrose; D000040:Abscisic Acid; D005966:Glucuronidase