title: Analysis of secondary growth in the Arabidopsis shoot reveals a positive role of jasmonate signalling in cambium formation.
abstract: After primary growth, most dicotyledonous plants undergo secondary growth. Secondary growth involves an increase in the diameter of shoots and roots through formation of secondary vascular tissue. A hallmark of secondary growth initiation in shoots of dicotyledonous plants is the initiation of meristematic activity between primary vascular bundles, i.e. in the interfascicular regions. This results in establishment of a cylindrical meristem, namely the vascular cambium. Surprisingly, despite its major implications for plant growth and the accumulation of biomass, the molecular regulation of secondary growth is only poorly understood. Here, we combine histological, molecular and genetic approaches to characterize interfascicular cambium initiation in the Arabidopsis thaliana inflorescence shoot. Using genome-wide transcriptional profiling, we show that stress-related and touch-inducible genes are up-regulated in stem regions where secondary growth takes place. Furthermore, we show that the products of COI1, MYC2, JAZ7 and the touch-inducible gene JAZ10, which are components of the JA signalling pathway, are cambium regulators. The positive effect of JA application on cambium activity confirmed a stimulatory role of JA in secondary growth, and suggests that JA signalling triggers cell divisions in this particular context.
authors.affiliation: Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Dr Bohr-Gasse 3, Vienna, Austria.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Sehr
authors.forename: Javier
authors.initials: J
authors.lastname: Agusti
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lehner
authors.forename: Edward E
authors.initials: EE
authors.lastname: Farmer
authors.forename: Martina
authors.initials: M
authors.lastname: Schwarz
authors.forename: Thomas
authors.initials: T
authors.lastname: Greb
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D058506:Cambium / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development*; D002455:Cell Division / Q000235:genetics; D003517:Cyclopentanes / Q000494:pharmacology*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018519:Meristem / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D054883:Oxylipins / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; C525049:JAS1 protein, Arabidopsis; C000602233:JAZ7 protein, Arabidopsis; C473611:MYC2 protein, Arabidopsis; D009687:Nuclear Proteins; D054883:Oxylipins; D010937:Plant Growth Regulators; D012097:Repressor Proteins; C011006:jasmonic acid