title: Arrangement of mixed-linkage glucan and glucuronoarabinoxylan in the cell walls of growing maize roots.
abstract: OBJECTIVE
  Plant cell enlargement is unambiguously coupled to changes in cell wall architecture, and as such various studies have examined the modification of the proportions and structures of glucuronoarabinoxylan and mixed-linkage glucan in the course of cell elongation in grasses. However, there is still no clear understanding of the mutual arrangement of these matrix polymers with cellulose microfibrils and of the modification of this architecture during cell growth. This study aimed to determine the correspondence between the fine structure of grass cell walls and the course of the elongation process in roots of maize (Zea mays).
  
  
  METHODS
  Enzymatic hydrolysis followed by biochemical analysis of derivatives was coupled with immunohistochemical detection of cell wall epitopes at different stages of cell development in a series of maize root zones.
  
  
  RESULTS
  Two xylan-directed antibodies (LM11 and ABX) have distinct patterns of primary cell wall labelling in cross-sections of growing maize roots. The LM11 epitopes were masked by mixed-linkage glucan and were revealed only after lichenase treatment. They could be removed from the section by xylanase treatment. Accessibility of ABX epitopes was not affected by the lichenase treatment. Xylanase treatment released only part of the cell wall glucuronoarabinoxylan and produced two types of products: high-substituted (released in polymeric form) and low-substituted (released as low-molecular-mass fragments). The amount of the latter was highly correlated with the amount of mixed-linkage glucan.
  
  
  CONCLUSIONS
  Three domains of glucuronoarabinoxylan were determined: one separating cellulose microfibrils, one interacting with them and a middle domain between the two, which links them. The middle domain is masked by the mixed-linkage glucan. A model is proposed in which the mixed-linkage glucan serves as a gel-like filler of the space between the separating domain of the glucuronoarabinoxylan and the cellulose microfibrils. Space for glucan is provided along the middle domain, the proportion of which increases during cell elongation.
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Science, Kazan, Lobachevskij str., 2/31, 420111, Russia bbinb@bk.ru.
authors.forename: L V
authors.initials: LV
authors.lastname: Kozlova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Science, Kazan, Lobachevskij str., 2/31, 420111, Russia.
authors.forename: M V
authors.initials: MV
authors.lastname: Ageeva
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Science, Kazan, Lobachevskij str., 2/31, 420111, Russia.
authors.forename: N N
authors.initials: NN
authors.lastname: Ibragimova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Science, Kazan, Lobachevskij str., 2/31, 420111, Russia.
authors.forename: T A
authors.initials: TA
authors.lastname: Gorshkova
mesh_terms: D000906:Antibodies; D002473:Cell Wall / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D005936:Glucans / Q000378:metabolism*; D006868:Hydrolysis; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D014990:Xylans / Q000276:immunology / Q000378:metabolism*; D003313:Zea mays / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000906:Antibodies; D005936:Glucans; D014990:Xylans; C114470:glucuronoarabinoxylan; D002482:Cellulose
keywords: Plant cell walls; Zea mays; cell expansion; cellulose; elongation growth; glucuronoarabinoxylan; maize; masking of polysaccharides; mixed-linkage glucan; primary root; type II cell walls
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