title: Stem cell activation by light guides plant organogenesis.
abstract: Leaves originate from stem cells located at the shoot apical meristem. The meristem is shielded from the environment by older leaves, and leaf initiation is considered to be an autonomous process that does not depend on environmental cues. Here we show that light acts as a morphogenic signal that controls leaf initiation and stabilizes leaf positioning. Leaf initiation in tomato shoot apices ceases in the dark but resumes in the light, an effect that is mediated through the plant hormone cytokinin. Dark treatment also affects the subcellular localization of the auxin transporter PIN1 and the concomitant formation of auxin maxima. We propose that cytokinin is required for meristem propagation, and that auxin redirects cytokinin-inducible meristem growth toward organ formation. In contrast to common wisdom over the last 150 years, the light environment controls the initiation of lateral organs by regulating two key hormones: auxin and cytokinin.
authors: Institute of Plant Sciences, University of Bern, CH-3013 Bern, Switzerland.
authors: Saiko
authors: S
authors: Yoshida
authors: Therese
authors: T
authors: Mandel
authors: Cris
authors: C
authors: Kuhlemeier
mesh_terms: D003583:Cytokinins / Q000378:metabolism / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D008027:Light; D018551:Solanum lycopersicum / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects*; D026901:Membrane Transport Proteins / Q000378:metabolism; D038081:Organogenesis / Q000187:drug effects / Q000528:radiation effects*; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D018520:Plant Shoots / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D018547:Plant Stems / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects*; D021381:Protein Transport / Q000528:radiation effects; D015398:Signal Transduction / Q000528:radiation effects
chemical_list: D003583:Cytokinins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D010937:Plant Growth Regulators