title: Cell wall composition and penetration resistance against the fungal pathogen Colletotrichum higginsianum are affected by impaired starch turnover in Arabidopsis mutants.
abstract: Penetration resistance represents the first level of plant defense against phytopathogenic fungi. Here, we report that the starch-deficient Arabidopsis thaliana phosphoglucomutase (pgm) mutant has impaired penetration resistance against the hemibiotrophic fungus Colletotrichum higginsianum. We could not determine any changes in leaf cutin and epicuticular wax composition or indolic glucosinolate levels, but detected complex alterations in the cell wall monosaccharide composition of pgm. Notably, other mutants deficient in starch biosynthesis (adg1) or mobilization (sex1) had similarly affected cell wall composition and penetration resistance. Glycome profiling analysis showed that both overall cell wall polysaccharide extractability and relative extractability of specific pectin and xylan epitopes were affected in pgm, suggesting extensive structural changes in pgm cell walls. Screening of mutants with alterations in content or modification of specific cell wall monosaccharides indicated an important function of pectic polymers for penetration resistance and hyphal growth of C. higginsianum during the biotrophic interaction phase. While mutants with affected pectic rhamnogalacturonan-I (mur8) were hypersusceptible, penetration frequency and morphology of fungal hyphae were impaired on pmr5 pmr6 mutants with increased pectin levels. Our results reveal a strong impact of starch metabolism on cell wall composition and suggest a link between carbohydrate availability, cell wall pectin and penetration resistance.
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Engelsdorf
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Will
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Hofmann
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Schmitt
authors.affiliation: Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA, USA.
authors.forename: Brian B
authors.initials: BB
authors.lastname: Merritt
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.
authors.forename: Leonie
authors.initials: L
authors.lastname: Rieger
authors.affiliation: Universität Bonn, Institute for Cellular and Molecular Botany, Department of Ecophysiology, Kirschallee 1,  Bonn, Germany.
authors.forename: Marc S
authors.initials: MS
authors.lastname: Frenger
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.|Technische Hochschule Nürnberg Georg-Simon Ohm, Nürnberg, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Marschall
authors.affiliation: Universität Bonn, Institute for Cellular and Molecular Botany, Department of Ecophysiology, Kirschallee 1,  Bonn, Germany.
authors.forename: Rochus B
authors.initials: RB
authors.lastname: Franke
authors.affiliation: Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA, USA.
authors.forename: Sivakumar
authors.initials: S
authors.lastname: Pattathil
authors.affiliation: Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.
authors.forename: Lars M
authors.initials: LM
authors.lastname: Voll
mesh_terms: D017360:Arabidopsis / Q000276:immunology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry*; D020231:Colletotrichum / Q000502:physiology*; D010368:Pectins / Q000378:metabolism*; D010733:Phosphoglucomutase / Q000235:genetics* / Q000378:metabolism; D013213:Starch / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D010368:Pectins; D013213:Starch; D010733:Phosphoglucomutase
keywords: Carbohydrate metabolism; cell wall; glycome profiling; hemibiotrophy; host–pathogen interaction; indolic glucosinolates; pectin; penetration resistance; plant defense; starch deficiency