title: The biosynthesis and wall-binding of hemicelluloses in cellulose-deficient maize cells: an example of metabolic plasticity.
abstract: Cell-suspension cultures (Zea mays L., Black Mexican sweet corn) habituated to 2,6-dichlorobenzonitrile (DCB) survive with reduced cellulose owing to hemicellulose network modification. We aimed to define the hemicellulose metabolism modifications in DCB-habituated maize cells showing a mild reduction in cellulose at different stages in the culture cycle. Using pulse-chase radiolabeling, we fed habituated and non-habituated cultures with [(3)H]arabinose, and traced the distribution of (3)H-pentose residues between xylans, xyloglucans and other polymers in several cellular compartments for 5 h. Habituated cells were slower taking up exogenous [(3)H]arabinose. Tritium was incorporated into polysaccharide-bound arabinose and xylose residues, but habituated cells diverted a higher proportion of their new [(3)H]xylose residues into (hetero) xylans at the expense of xyloglucan synthesis. During logarithmic growth, habituated cells showed slower vesicular trafficking of polymers, especially xylans. Moreover, habituated cells showed a decrease in the strong wall-binding of all pentose-containing polysaccharides studied; correspondingly, especially in log-phase cultures, habituation increased the proportion of (3)H-hemicelluloses ([(3)H]xylans and [(3)H]xyloglucan) sloughed into the medium. These findings could be related to the cell walls' cellulose-deficiency, and consequent reduction in binding sites for hemicelluloses; the data could also reflect the habituated cells' reduced capacity to integrate arabinoxylans by extra-protoplasmic phenolic cross-linking, as well as xyloglucans, during wall assembly.
authors.affiliation: The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, Daniel Rutherford Building, The King's Buildings, Edinburgh, EH9 3JH, UK; Laboratory of Plant Physiology, Faculty of Biological and Environmental Sciences, University of Léon, E-24071, León, Spain.
authors.forename: María
authors.initials: M
authors.lastname: de Castro
authors.forename: Janice G
authors.initials: JG
authors.lastname: Miller
authors.forename: José Luis
authors.initials: JL
authors.lastname: Acebes
authors.forename: Antonio
authors.initials: A
authors.lastname: Encina
authors.forename: Penélope
authors.initials: P
authors.lastname: García-Angulo
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Fry
mesh_terms: D001089:Arabinose / Q000378:metabolism; D002451:Cell Compartmentation / Q000187:drug effects; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D005936:Glucans / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D007700:Kinetics; D009570:Nitriles / Q000494:pharmacology; D011134:Polysaccharides / Q000096:biosynthesis* / Q000378:metabolism; D014316:Tritium / Q000378:metabolism; D014990:Xylans / Q000378:metabolism; D003313:Zea mays / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D005936:Glucans; D009570:Nitriles; D011134:Polysaccharides; D014990:Xylans; D014316:Tritium; C029353:xyloglucan; C007916:hemicellulose; D002482:Cellulose; C014356:benzonitrile; D001089:Arabinose; D006026:Glycoside Hydrolases; C035212:driselase
keywords: 2,6-dichlorobenzonitrile; Arabinoxylan; Hemicellulose biosynthesis; cell wall cross-linking; xyloglucan