title: Water stress and cell wall polysaccharides in the apical root zone of wheat cultivars varying in drought tolerance.
abstract: Glycosyl composition and linkage analysis of cell wall polysaccharides were examined in apical root zones excised from water-stressed and unstressed wheat seedlings (Triticum durum Desf.) cv. Capeiti ("drought-tolerant") and cv. Creso ("drought sensitive"). Wall polysaccharides were sequentially solubilized to obtain three fractions: CDTA+Na(2)CO(3) extract, KOH extract and the insoluble residue (alpha-cellulose). A comparison between the two genotypes showed only small variations in the percentages of matrix polysaccharides (CDTA+Na(2)CO(3) plus KOH extract) and of the insoluble residues (alpha-cellulose) in water-stressed and unstressed conditions. Xylosyl, glucosyl and arabinosyl residues represented more than 90 mol% of the matrix polysaccharides. The linkage analysis of matrix polysaccharides showed high levels of xyloglucans (23-39 mol%), and arabinoxylans (38-48 mol%) and a low amount of pectins and (1-->3), (1-->4)-beta-D-glucans. The high level of xyloglucans was supported by the release of the diagnostic disaccharide isoprimeverose after Driselase digestion of KOH-extracted polysaccharides. In the "drought-tolerant" cv. Capeiti the mol% of side chains of rhamnogalacturonan I and II significantly increased in response to water stress, whereas in cv. Creso, this increase did not occur. The results support a role of the pectic side chains during water stress response in a drought-tolerant wheat cultivar.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università del Salento, Lecce, Italy.
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Leucci
authors.forename: Marcello Salvatore
authors.initials: MS
authors.lastname: Lenucci
authors.forename: Gabriella
authors.initials: G
authors.lastname: Piro
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Dalessandro
mesh_terms: D000222:Adaptation, Physiological; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D016764:Cell Polarity; D002473:Cell Wall / Q000737:chemistry*; D002852:Chromatography, Ion Exchange; D003681:Dehydration; D004187:Disaccharides / Q000378:metabolism; D055864:Droughts; D004586:Electrophoresis; D005656:Fungal Proteins / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006868:Hydrolysis; D006878:Hydroxides; D008969:Molecular Sequence Data; D010936:Plant Extracts / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology* / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D017680:Potassium Compounds; D036226:Seedlings / Q000378:metabolism; D014908:Triticum / Q000166:cytology* / Q000378:metabolism
chemical_list: D004187:Disaccharides; D005656:Fungal Proteins; D006878:Hydroxides; D010936:Plant Extracts; D011134:Polysaccharides; D017680:Potassium Compounds; C046205:isoprimeverose; D006026:Glycoside Hydrolases; C035212:driselase; C029943:potassium hydroxide