title: Ethylene Inhibits Root Elongation during Alkaline Stress through AUXIN1 and Associated Changes in Auxin Accumulation.
abstract: Soil alkalinity causes major reductions in yield and quality of crops worldwide. The plant root is the first organ sensing soil alkalinity, which results in shorter primary roots. However, the mechanism underlying alkaline stress-mediated inhibition of root elongation remains to be further elucidated. Here, we report that alkaline conditions inhibit primary root elongation of Arabidopsis (Arabidopsis thaliana) seedlings by reducing cell division potential in the meristem zones and that ethylene signaling affects this process. The ethylene perception antagonist silver (Ag(+)) alleviated the inhibition of root elongation by alkaline stress. Moreover, the ethylene signaling mutants ethylene response1-3 (etr1-3), ethylene insensitive2 (ein2), and ein3-1 showed less reduction in root length under alkaline conditions, indicating a reduced sensitivity to alkalinity. Ethylene biosynthesis also was found to play a role in alkaline stress-mediated root inhibition; the ethylene overproducer1-1 mutant, which overproduces ethylene because of increased stability of 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE5, was hypersensitive to alkaline stress. In addition, the ethylene biosynthesis inhibitor cobalt (Co(2+)) suppressed alkaline stress-mediated inhibition of root elongation. We further found that alkaline stress caused an increase in auxin levels by promoting expression of auxin biosynthesis-related genes, but the increase in auxin levels was reduced in the roots of the etr1-3 and ein3-1 mutants and in Ag(+)/Co(2+)-treated wild-type plants. Additional genetic and physiological data showed that AUXIN1 (AUX1) was involved in alkaline stress-mediated inhibition of root elongation. Taken together, our results reveal that ethylene modulates alkaline stress-mediated inhibition of root growth by increasing auxin accumulation by stimulating the expression of AUX1 and auxin biosynthesis-related genes.
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China (J.L., W.-C.L., X.-W.Z., Y.-T.L.); andJiangsu Key Laboratory of Marine Pharmaceutical Compound Screening and Co-Innovation Center for Jiangsu Marine Bio-Industry Technology, Huaihai Institute of Technology, Lianyungang 222005, China (H.-H.X.).
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China (J.L., W.-C.L., X.-W.Z., Y.-T.L.); andJiangsu Key Laboratory of Marine Pharmaceutical Compound Screening and Co-Innovation Center for Jiangsu Marine Bio-Industry Technology, Huaihai Institute of Technology, Lianyungang 222005, China (H.-H.X.).
authors.forename: Heng-Hao
authors.initials: HH
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China (J.L., W.-C.L., X.-W.Z., Y.-T.L.); andJiangsu Key Laboratory of Marine Pharmaceutical Compound Screening and Co-Innovation Center for Jiangsu Marine Bio-Industry Technology, Huaihai Institute of Technology, Lianyungang 222005, China (H.-H.X.).
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China (J.L., W.-C.L., X.-W.Z., Y.-T.L.); andJiangsu Key Laboratory of Marine Pharmaceutical Compound Screening and Co-Innovation Center for Jiangsu Marine Bio-Industry Technology, Huaihai Institute of Technology, Lianyungang 222005, China (H.-H.X.).
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China (J.L., W.-C.L., X.-W.Z., Y.-T.L.); andJiangsu Key Laboratory of Marine Pharmaceutical Compound Screening and Co-Innovation Center for Jiangsu Marine Bio-Industry Technology, Huaihai Institute of Technology, Lianyungang 222005, China (H.-H.X.) yingtlu@whu.edu.cn.
authors.forename: Ying-Tang
authors.identifier: http://orcid.org/0000-0002-8875-9091
authors.initials: YT
authors.lastname: Lu
mesh_terms: D000468:Alkalies / Q000737:chemistry; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration; D007210:Indoleacetic Acids / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012835:Silver Nitrate / Q000494:pharmacology; D012987:Soil / Q000737:chemistry; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: C100794:AUX1 protein, Arabidopsis; D000468:Alkalies; D029681:Arabidopsis Proteins; C119963:EIN2 protein, Arabidopsis; C494590:ETR1 protein, Arabidopsis; D005030:Ethylenes; D007210:Indoleacetic Acids; D008164:Luminescent Proteins; D011956:Receptors, Cell Surface; D012987:Soil; C036216:ethylene; D012835:Silver Nitrate