The Plant journal : for cell and molecular biology 20040701 2
We have developed a versatile floral induction system that is based on ectopic overexpression of the transcription factor LEAFY (LFY) in callus. During shoot regeneration, flowers or floral organs are formed directly from root explants without prior formation of rosette leaves. Morphological and reporter gene analyses show that leaf-like structures are converted to floral organs in response to LFY activity. Thus, increased levels of LFY activity are sufficient to bypass normal vegetative develop ...[more]
Project description:Wounding is a primary trigger of organ regeneration but how wound stress reactivates cell proliferation and promotes cellular reprogramming remains elusive. In this study we combined the transcriptome analysis with quantitative hormonal analysis to investigate how wounding induces callus formation in Arabidopsis thaliana. Our time-course RNA-seq analysis revealed that wounding induces dynamic transcriptional changes that can be categorized into five clusters with distinct temporal patterns. Gene ontology analyses uncovered that wounding modifies the expression of hormone biosynthesis and response genes, and quantitative analysis of endogenous plant hormones revealed accumulation of cytokinin prior to callus formation. Mutants defective in cytokinin synthesis and signalling display reduced efficiency in callus formation, indicating that de novo synthesis of cytokinin has major contribution in wound-induced callus formation. We further demonstrate that type-A ARABIDOPSIS RESPONSE REGULATOR (ARR)-mediated cytokinin signalling regulates the expression of CYCLIN D3;1 (CYCD3;1) and mutations in CYCD3;1 and its homologs CYCD3;2-3 cause defects in callus formation. Our transcriptome data, in addition, showed that wounding activates multiple developmental regulators, and we found novel roles of ETHYLENE RESPONSE FACTOR 115 (ERF115) and PLETHORA3 (PLT3), PLT5, PLT7 in wound-induced callus formation. Together, this study provides novel mechanistic insights into how wounding reactivates cell proliferation during callus formation. Overall design: Examination of transcriptome at 0, 1, 3, 6, 12,24 h after wounding.
Project description:Callus derived from 35S:LFY-GR plants was treated with dexamethasone- or was mock-treated for 0,2,4,6,8,10,12, or 22 hours. Four biologically independent sets of samples were generated and RNA probes derived from these samples were co-hybridized to a cDNA array enriched for flower-specific transcripts. The data were analyzed with Rosetta Resolver as described in Wagner et al. (2004). Keywords: time-course
Project description:Global analysis of gene expression in 9 day old LEAFY-GR, 35S::LFY or Landsberg erecta seedlings treated with the steroid dexamethasone and/or the protein synthesis inhibitor cycloheximide.
Project description:This experiment describes gene expression during early Arabidopsis flower development. We used a 35S:AP1-GR ap1 cal line to induce synchronized flower development by specifically activating the AP1-GR fusion protein in ap1 cal inflorescence-like meristems through dexamethasone treatment. Tissue samples were collected immediately after the treatment, as well as at one-day intervals for the following five days. The expression profiles of the individual samples were then analyzed by gene expression profiling using whole-genome microarrays (Operon). Keywords: time course Overall design: Four sets of biologically independent tissue samples were collect 0,1,2,3,4, and 5 days after activation of the AP1-GR fusion protein. Samples of consecutive time points from each set were co-hybridized to micoarrays. Dyes used for labeling the RNA populations derived from the individual samples were switched in the replicate experiments to reduce dye-related artefacts.