title: Cell wall modifications in Arabidopsis plants with altered alpha-L-arabinofuranosidase activity.
abstract: Although cell wall remodeling is an essential feature of plant growth and development, the underlying molecular mechanisms are poorly understood. This work describes the characterization of Arabidopsis (Arabidopsis thaliana) plants with altered expression of ARAF1, a bifunctional alpha-L-arabinofuranosidase/beta-D-xylosidase (At3g10740) belonging to family 51 glycosyl-hydrolases. ARAF1 was localized in several cell types in the vascular system of roots and stems, including xylem vessels and parenchyma cells surrounding the vessels, the cambium, and the phloem. araf1 T-DNA insertional mutants showed no visible phenotype, whereas transgenic plants that overexpressed ARAF1 exhibited a delay in inflorescence emergence and altered stem architecture. Although global monosaccharide analysis indicated only slight differences in cell wall composition in both mutant and overexpressing lines, immunolocalization experiments using anti-arabinan (LM6) and anti-xylan (LM10) antibodies indicated cell type-specific alterations in cell wall structure. In araf1 mutants, an increase in LM6 signal intensity was observed in the phloem, cambium, and xylem parenchyma in stems and roots, largely coinciding with ARAF1 expression sites. The ectopic overexpression of ARAF1 resulted in an increase in LM10 labeling in the secondary walls of interfascicular fibers and xylem vessels. The combined ARAF1 gene expression and immunolocalization studies suggest that arabinan-containing pectins are potential in vivo substrates of ARAF1 in Arabidopsis.
authors.affiliation: UMR 5546, CNRS-Université Paul Sabatier, Surfaces Cellulaires et Signalisation chez les Végétaux, BP 42617 Auzeville, 31326 Castanet-Tolosan, France.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Chávez Montes
authors.forename: Philippe
authors.initials: P
authors.lastname: Ranocha
authors.forename: Yves
authors.initials: Y
authors.lastname: Martinez
authors.forename: Zoran
authors.initials: Z
authors.lastname: Minic
authors.forename: Lise
authors.initials: L
authors.lastname: Jouanin
authors.forename: Mélanie
authors.initials: M
authors.lastname: Marquis
authors.forename: Luc
authors.initials: L
authors.lastname: Saulnier
authors.forename: Lynette M
authors.initials: LM
authors.lastname: Fulton
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Cobbett
authors.forename: Frédérique
authors.initials: F
authors.lastname: Bitton
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Renou
authors.forename: Alain
authors.initials: A
authors.lastname: Jauneau
authors.forename: Deborah
authors.initials: D
authors.lastname: Goffner
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D004269:DNA, Bacterial; D015870:Gene Expression; D020869:Gene Expression Profiling; D005966:Glucuronidase / Q000378:metabolism; D007150:Immunohistochemistry; D009005:Monosaccharides / Q000378:metabolism; D016254:Mutagenesis, Insertional; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D018547:Plant Stems / Q000254:growth & development; D011134:Polysaccharides / Q000378:metabolism*; D014995:Xylosidases / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D009005:Monosaccharides; D011134:Polysaccharides; C036483:T-DNA; C030080:araban; C488780:ARAf protein, Arabidopsis; D014995:Xylosidases; D005966:Glucuronidase