title: ANAC032 Positively Regulates Age-Dependent and Stress-Induced Senescence in Arabidopsis thaliana.
abstract: Members of the NAC transcription factor family have been implicated in the regulation of different processes of plant development including senescence. In this study, the role of ANAC032 is analyzed in Arabidopsis thaliana (Col-0). ANAC032 is shown to act as a transcriptional activator and its expression is induced in senescing leaves as well as in dark-treated detached leaves. Analysis of transgenic overexpressors (OXs) and chimeric repressors (SRDXs) of ANAC032 indicates that ANAC032 positively regulates age-dependent and dark-induced leaf senescence. Quantitative real-time PCR analysis showed that ANAC032 regulates leaf senescence mainly through the modulation of expression of the senescence-associated genes AtNYE1, SAG113 and SAUR36/SAG201, which are involved in Chl degradation, and ABA and auxin promotion of senescence, respectively. In addition, ANAC032 expression is induced by a range of oxidative and abiotic stresses. As a result, ANAC032 overexpression lines exhibited enhanced leaf senescence when challenged with different oxidative (3-aminotriazole, fumonisin B1 and high light) and abiotic stress (osmotic and salinity) conditions compared with the wild type. In contrast, ANAC032 SRDX lines displayed the opposite phenotype. ANAC032 transgenic lines showed altered 2,4-D-mediated root tip swelling and root inhibition responses when compared with the wild type. The altered response to auxin, oxidative and abiotic stress treatments in ANAC032 transgenic lines involves differential accumulation of H2O2compared with the wild type. Taken together, these results indicate that ANAC032 is an important transcription factor that positively regulates age-dependent and stress-induced senescence in A. thaliana by modulating reactive oxygen species production.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Kashif
authors.initials: K
authors.lastname: Mahmood
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.|Present address: Division of Agriculture and Natural Resources, University of California, Cooperative Extension Kern County, Bakersfield, CA, USA.
authors.forename: Ashraf
authors.initials: A
authors.lastname: El-Kereamy
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Sung-Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada.
authors.forename: Eiji
authors.initials: E
authors.lastname: Nambara
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada rothstei@uoguelph.ca.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Rothstein
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology; D009995:Osmosis / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics; D030821:Plants, Genetically Modified; D021381:Protein Transport / Q000187:drug effects; D012097:Repressor Proteins / Q000378:metabolism; D054712:Salinity; D013312:Stress, Physiological / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: C000616075:ANAC032 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D012097:Repressor Proteins; D015534:Trans-Activators; D002734:Chlorophyll; D006861:Hydrogen Peroxide
keywords: 
  Arabidopsis thaliana
  ; ANAC032; Auxin; ROS production; Senescence; Stress