title: Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level.
abstract: BACKGROUND
  Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility.
  
  
  RESULTS
  We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA) mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1) from Aspergillus aculeatus, then hypocotyl elongation is reduced.
  
  
  CONCLUSIONS
  Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.
authors.affiliation: Department of Metabolic Biology, John Innes Centre, Norwich, UK. paul.derbyshire@bbsrc.ac.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Derbyshire
authors.forename: Maureen C
authors.initials: MC
authors.lastname: McCann
authors.forename: Keith
authors.initials: K
authors.lastname: Roberts
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D002455:Cell Division; D004951:Esterification; D018546:Hypocotyl / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D010368:Pectins / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase