title: The pattern of distribution of pectin, peroxidase and lignin in the middle lamella of secondary xylem fibres in alfalfa (Medicago sativa).
abstract: OBJECTIVE
  Information on the micro-distribution of lignin within the middle lamella is only just beginning to emerge. This paper provides evidence of marked heterogeneity in the micro-distribution of lignin, pectin, peroxidase and hydrogen peroxide in the middle lamella of alfalfa (Medicago sativa).
  
  
  METHODS
  Specimens from alfalfa stems were collected and processed for transmission electron microscopy. The middle lamella architecture was examined prior to and during lignification, using transmission electron microscopy in combination with pectin- and lignin-specific staining. In addition, immuno-gold labelling of peroxidase and cytochemical localization of hydrogen peroxide (H2O2) were undertaken.
  
  
  RESULTS
  Lignin showed inhomogeneity in its distribution in the middle lamella. It was found that the distribution of pectin was irregular and corresponded to the pattern of deposited lignin. Additionally, a similarity in the pattern of the deposited lignin to the pattern of distribution of peroxidase and H2O2 was also observed.
  
  
  CONCLUSIONS
  Irregular distribution of pectin in the middle lamella may be related to subsequent inhomegeneity in lignin in this region.
authors.affiliation: College of Agriculture and Life Sciences, Chonnam National University, Yongbong-dong 300, Buk-gu, Gwangju, 500-757 Korea.
authors.forename: S G
authors.initials: SG
authors.lastname: Wi
authors.forename: A P
authors.initials: AP
authors.lastname: Singh
authors.forename: K H
authors.initials: KH
authors.lastname: Lee
authors.forename: Y S
authors.initials: YS
authors.lastname: Kim
mesh_terms: D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007150:Immunohistochemistry; D008031:Lignin / Q000378:metabolism*; D000455:Medicago sativa / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D010368:Pectins / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism*; D018514:Plant Structures / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D010368:Pectins; D008031:Lignin; D006861:Hydrogen Peroxide; D009195:Peroxidase