title: Proteome analysis of apical and basal regions of poplar stems under gravitropic stimulation.
abstract: Gravity is a constant force guiding the direction of plant growth. In young poplar stem, reorientation of the apical region is mainly obtained by differential growth of elongating primary tissues. At the base, where elongation is achieved but where the cambium is active, reorientation is due to asymmetrical formation of reaction wood. After 45 min of gravistimulation, the stem showed no reorientation, but 1 week later, reaction wood was observed at the base of the stem. To determine the molecular mechanisms taking place at the top and base of the stem, after 45 min or 1 week of inclination, the changes induced in protein accumulation were studied by two-dimensional polyacrylamide gel electrophoresis and quantitatively analyzed using image analysis software. Around 300 protein spots were reproducibly detected and analyzed. Forty percent of these proteins showed significant changes after inclination. Mass spectrometry analysis of 135 spots led to the identification of 60 proteins involved in a wide range of activities and metabolisms. Very different patterns of protein expression were obtained according to conditions tested, highlighting the complexity of gravitropic responses. Our results suggest that primary and secondary tissues present specific mechanisms to sense reorientation and to respond to inclination. Some selected proteins are discussed.
authors.affiliation: Université Blaise Pascal, UMR547 PIAF, 24 av des Landais, F-63177 Aubière, France.
authors.forename: Wassim
authors.initials: W
authors.lastname: Azri
authors.forename: Christophe
authors.initials: C
authors.lastname: Chambon
authors.forename: Stéphane
authors.initials: S
authors.lastname: Herbette
authors.forename: Nicole
authors.initials: N
authors.lastname: Brunel
authors.forename: Catherine
authors.initials: C
authors.lastname: Coutand
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Leplé
authors.forename: Ichrak
authors.initials: I
authors.lastname: Ben Rejeb
authors.forename: Saïda
authors.initials: S
authors.lastname: Ammar
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Julien
authors.forename: Patricia
authors.initials: P
authors.lastname: Roeckel-Drevet
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D018506:Gene Expression Regulation, Plant; D018522:Gravitropism / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism*; D018547:Plant Stems / Q000378:metabolism* / Q000502:physiology; D032107:Populus / Q000378:metabolism / Q000502:physiology*; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D010940:Plant Proteins