title: Rapid auxin-mediated changes in the proteome of the epidermal cells in rye coleoptiles: implications for the initiation of growth.
abstract: In axial organs of juvenile plants, the phytohormone auxin (indole-3-acetic acid, IAA) rapidly mediates cell wall loosening and hence promotes turgor-driven elongation. In this study, we used rye (Secale cereale) coleoptile sections to investigate possible effects of IAA on the proteome of the cells. In a first set of experiments, we document that IAA causes organ elongation via promotion of expansion of the rigid outer wall of the outer epidermis. A quantitative comparison of the proteome (membrane-associated proteins), using two-dimensional difference gel electrophoresis (2-D DIGE), revealed that, within 2 h of auxin treatment, at least 16 protein spots were up- or down-regulated by IAA. These proteins were identified using reverse-phase liquid chromatography electrospray tandem mass spectrometry. Four of these proteins were detected in the growth-controlling outer epidermis and were further analysed. One epidermal polypeptide, a small Ras-related GTP-binding protein, was rapidly down-regulated by IAA (after 0.5 h of incubation) by -35% compared to the control. Concomitantly, a subunit of the 26S proteasome was up-regulated by IAA (+30% within 1 h). In addition, this protein displayed IAA-mediated post-translational modification. The implications of these rapid auxin effects with respect to signal transduction and IAA-mediated secretion of glycoproteins (osmiophilic nano-particles) into the growth-controlling outer epidermal wall are discussed.
authors: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA.
authors: Z
authors: Z
authors: Deng
authors: S
authors: S
authors: Xu
authors: R J
authors: RJ
authors: Chalkley
authors: J A
authors: JA
authors: Oses-Prieto
authors: A L
authors: AL
authors: Burlingame
authors: Z-Y
authors: ZY
authors: Wang
authors: U
authors: U
authors: Kutschera
mesh_terms: D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D018548:Cotyledon / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D019441:Plant Epidermis / Q000187:drug effects / Q000254:growth & development; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000378:metabolism*; D020543:Proteome / Q000187:drug effects / Q000378:metabolism*; D012434:Secale / Q000187:drug effects / Q000378:metabolism*
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D020543:Proteome; C030737:indoleacetic acid