title: Auxin Resistant1 and PIN-FORMED2 Protect Lateral Root Formation in Arabidopsis under Iron Stress.
abstract: A stunted root system is a significant symptom of iron (Fe) toxicity, yet little is known about the effects of excess Fe on lateral root (LR) development. In this work, we show that excess Fe has different effects on LR development in different portions of the Arabidopsis (Arabidopsis thaliana) root system and that inhibitory effects on the LR initiation are only seen in roots newly formed during excess Fe exposure. We show that root tip contact with Fe is both necessary and sufficient for LR inhibition and that the auxin, but not abscisic acid, pathway is engaged centrally in the initial stages of excess Fe exposure. Furthermore, Fe stress significantly reduced PIN-FORMED2 (PIN2)-green fluorescent protein (GFP) expression in root tips, and pin2-1 mutants exhibited significantly fewer LR initiation events under excess Fe than the wild type. Exogenous application of both Fe and glutathione together increased PIN2-GFP expression and the number of LR initiation events compared with Fe treatment alone. The ethylene inhibitor aminoethoxyvinyl-glycine intensified Fe-dependent inhibition of LR formation in the wild type, and this inhibition was significantly reduced in the ethylene overproduction mutant ethylene overproducer1-1. We show that Auxin Resistant1 (AUX1) is a critical component in the mediation of endogenous ethylene effects on LR formation under excess Fe stress. Our findings demonstrate the relationship between excess Fe-dependent PIN2 expression and LR formation and the potential role of AUX1 in ethylene-mediated LR tolerance and suggest that AUX1 and PIN2 protect LR formation in Arabidopsis during the early stages of Fe stress.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China (G.L., H.S., B.L., W.S.); andDepartment of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4 (H.J.K.).
authors.forename: Guangjie
authors.identifier: http://orcid.org/0000-0003-4603-6722
authors.initials: G
authors.lastname: Li
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China (G.L., H.S., B.L., W.S.); andDepartment of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4 (H.J.K.).
authors.forename: Haiyan
authors.initials: H
authors.lastname: Song
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China (G.L., H.S., B.L., W.S.); andDepartment of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4 (H.J.K.).
authors.forename: Baohai
authors.identifier: http://orcid.org/0000-0002-9905-5890
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, China (G.L., H.S., B.L., W.S.); andDepartment of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4 (H.J.K.).
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, China (G.L., H.S., B.L., W.S.); andDepartment of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4 (H.J.K.) wmshi@issas.ac.cn.
authors.forename: Weiming
authors.initials: W
authors.lastname: Shi
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism; D017930:Genes, Reporter; D005838:Genotype; D007210:Indoleacetic Acids / Q000378:metabolism; D007501:Iron / Q000633:toxicity; D018519:Meristem / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D009154:Mutation; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D013312:Stress, Physiological
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D005030:Ethylenes; D007210:Indoleacetic Acids; D007501:Iron; D010937:Plant Growth Regulators; C100794:AUX1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis; C036216:ethylene