title: The Arabidopsis thaliana FASCICLIN LIKE ARABINOGALACTAN PROTEIN 4 gene acts synergistically with abscisic acid signalling to control root growth.
abstract: OBJECTIVE
  The putative FASCICLIN-LIKE ARABINOGALACTAN PROTEIN 4 (At-FLA4) locus of Arabidopsis thaliana has previously been shown to be required for the normal growth of wild-type roots in response to moderately elevated salinity. However, the genetic and physiological pathway that connects At-FLA4 and normal root growth remains to be elucidated.
  
  
  METHODS
  The radial swelling phenotype of At-fla4 was modulated with growth regulators and their inhibitors. The relationship of At-FLA4 to abscisic acid (ABA) signalling was analysed by probing marker gene expression and the observation of the At-fla4 phenotype in combination with ABA signalling mutants.
  
  
  RESULTS
  Application of ABA suppresses the non-redundant role of At-FLA4 in the salt response. At-FLA4 positively regulates the response to low ABA concentration in roots and is required for the normal expression of ABA- and abiotic stress-induced genes. The At-fla4 phenotype is enhanced in the At-abi4 background, while two genetic suppressors of ABA-induced gene expression are required for salt oversensitivity of At-fla4. Salt oversensitivity in At-fla4 is suppressed by the CYP707A inhibitor abscinazole E2B, and salt oversensitivity in At-fla4 roots is phenocopied by chemical inhibition of ABA biosynthesis.
  
  
  CONCLUSIONS
  The predicted lipid-anchored glycoprotein At-FLA4 positively regulates cell wall biosynthesis and root growth by modulating ABA signalling.
authors.affiliation: University of Natural Resources and Life Science, Vienna, Austria; Department of Applied Genetics and Cell Biology, Muthgasse 18, A-1990 Vienna, Austria georg.seifert@boku.ac.at.
authors.forename: Georg J
authors.initials: GJ
authors.lastname: Seifert
authors.affiliation: University of Natural Resources and Life Science, Vienna, Austria; Department of Applied Genetics and Cell Biology, Muthgasse 18, A-1990 Vienna, Austria.
authors.forename: Hui
authors.initials: H
authors.lastname: Xue
authors.affiliation: University of Natural Resources and Life Science, Vienna, Austria; Department of Applied Genetics and Cell Biology, Muthgasse 18, A-1990 Vienna, Austria Gümüşhane University, School of Health & Nursing, 29100 Gümüşhane, Turkey Karadeniz Technical University, Science Faculty, Department of Biology, 61080 Trabzon, Turkey.
authors.forename: Tuba
authors.initials: T
authors.lastname: Acet
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects; D018506:Gene Expression Regulation, Plant; D008957:Models, Genetic; D009088:Mucoproteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D014230:Triazoles / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D009088:Mucoproteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014230:Triazoles; C574130:abscinazole-E2B; C006619:arabinogalactan proteins; D012965:Sodium Chloride; D000040:Abscisic Acid; D003577:Cytochrome P-450 Enzyme System; C107203:abscisic acid 8'-hydroxylase
keywords: Arabidopsis thaliana; At-FLA4; Fasciclin; abscisic acid; arabinogalactan protein; cell wall; plant cell wall signalling; root growth