title: Ethylene Inhibits Cell Proliferation of the Arabidopsis Root Meristem.
abstract: The root system of plants plays a critical role in plant growth and survival, with root growth being dependent on both cell proliferation and cell elongation. Multiple phytohormones interact to control root growth, including ethylene, which is primarily known for its role in controlling root cell elongation. We find that ethylene also negatively regulates cell proliferation at the root meristem of Arabidopsis (Arabidopsis thaliana). Genetic analysis indicates that the inhibition of cell proliferation involves two pathways operating downstream of the ethylene receptors. The major pathway is the canonical ethylene signal transduction pathway that incorporates CONSTITUTIVE TRIPLE RESPONSE1, ETHYLENE INSENSITIVE2, and the ETHYLENE INSENSITIVE3 family of transcription factors. The secondary pathway is a phosphorelay based on genetic analysis of receptor histidine kinase activity and mutants involving the type B response regulators. Analysis of ethylene-dependent gene expression and genetic analysis supports SHORT HYPOCOTYL2, a repressor of auxin signaling, as one mediator of the ethylene response and furthermore, indicates that SHORT HYPOCOTYL2 is a point of convergence for both ethylene and cytokinin in negatively regulating cell proliferation. Additional analysis indicates that ethylene signaling contributes but is not required for cytokinin to inhibit activity of the root meristem. These results identify key elements, along with points of cross talk with cytokinin and auxin, by which ethylene negatively regulates cell proliferation at the root apical meristem.
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Ian H
authors.identifier: http://orcid.org/0000-0002-1113-1415
authors.initials: IH
authors.lastname: Street
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Sitwat
authors.initials: S
authors.lastname: Aman
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Yan
authors.initials: Y
authors.lastname: Zubo
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Aleena
authors.identifier: http://orcid.org/0000-0003-1095-1670
authors.initials: A
authors.lastname: Ramzan
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Samina N
authors.initials: SN
authors.lastname: Shakeel
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.).
authors.forename: Joseph J
authors.identifier: http://orcid.org/0000-0002-5766-812X
authors.initials: JJ
authors.lastname: Kieber
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755 (I.H.S., S.A., Y.Z., A.R., X.W., G.E.S.); Department of Biochemistry, Quaid-i-azam University, Islamabad 45320, Pakistan (S.A., A.R., S.N.S.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.) george.e.schaller@dartmouth.edu.
authors.forename: G Eric
authors.identifier: http://orcid.org/0000-0003-4032-2437
authors.initials: GE
authors.lastname: Schaller
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects; D029681:Arabidopsis Proteins / Q000378:metabolism; D053145:Cell Nucleus Size / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003583:Cytokinins / Q000494:pharmacology; D005030:Ethylenes / Q000494:pharmacology*; D000071677:Histidine Kinase; D018519:Meristem / Q000166:cytology* / Q000187:drug effects; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D005030:Ethylenes; D009687:Nuclear Proteins; D011956:Receptors, Cell Surface; C117994:SHY2 protein, Arabidopsis; C036216:ethylene; D011494:Protein Kinases; D000071677:Histidine Kinase