title: Identification of genes involved in the ACC-mediated control of root cell elongation in Arabidopsis thaliana.
abstract: BACKGROUND
  Along the root axis of Arabidopsis thaliana, cells pass through different developmental stages. In the apical meristem repeated cycles of division increase the numbers of cells. Upon leaving the meristem, these cells pass the transition zone where they are physiologically and mechanically prepared to undergo subsequent rapid elongation. During the process of elongation epidermal cells increase their length by 300% in a couple of hours. When elongation ceases, the cells acquire their final size, shape and functions (in the differentiation zone). Ethylene administered as its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) is capable of inhibiting elongation in a concentration-dependent way. Using a microarray analysis, genes and/or processes involved in this elongation arrest are identified.
  
  
  RESULTS
  Using a CATMA-microarray analysis performed on control and 3h ACC-treated roots, 240 differentially expressed genes were identified. Quantitative Real-Time RT-PCR analysis of the 10 most up and down regulated genes combined with literature search confirmed the accurateness of the analysis. This revealed that inhibition of cell elongation is, at least partly, caused by restricting the events that under normal growth conditions initiate elongation and by increasing the processes that normally stop cellular elongation at the end of the elongation/onset of differentiation zone.
  
  
  CONCLUSIONS
  ACC interferes with cell elongation in the Arabidopsis thaliana roots by inhibiting cells from entering the elongation process and by immediately stimulating the formation of cross-links in cell wall components, diminishing the remaining elongation capacity. From the analysis of the differentially expressed genes, it becomes clear that many genes identified in this response, are also involved in several other kind of stress responses. This suggests that many responses originate from individual elicitors, but that somewhere in the downstream signaling cascade, these are converged to a 'common pathway'. Furthermore, several potential keyplayers, such as transcription factors and auxin-responsive genes, were identified by the microarray analysis. They await further analysis to reveal their exact role in the control of cell elongation.
authors.affiliation: Biology Dept,, Plant Growth and Development, Univ, Antwerp, Groenenborgerlaan 171, Antwerpen, 2020, Belgium.
authors.forename: Marios Nektarios
authors.initials: MN
authors.lastname: Markakis
authors.forename: Tinne
authors.initials: T
authors.lastname: De Cnodder
authors.forename: Michal
authors.initials: M
authors.lastname: Lewandowski
authors.forename: Damien
authors.initials: D
authors.lastname: Simon
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Boron
authors.forename: Daria
authors.initials: D
authors.lastname: Balcerowicz
authors.forename: Thanaa
authors.initials: T
authors.lastname: Doubbo
authors.forename: Ludivine
authors.initials: L
authors.lastname: Taconnat
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Renou
authors.forename: Herman
authors.initials: H
authors.lastname: Höfte
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Verbelen
authors.forename: Kris
authors.initials: K
authors.lastname: Vissenberg
mesh_terms: D000598:Amino Acids, Cyclic / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D018517:Plant Roots / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000598:Amino Acids, Cyclic; C023863:1-aminocyclopropane-1-carboxylic acid