Project description:Transcriptional profiling of Arabidopsis thaliana seedlings treated with auxin (indole-3-acetic acid), highlighting to the physiological function of auxin by observing early response of gene expressions in Arabidopsis seedlings.
Project description:A mutant screen was conducted in Arabidopsis that was based on deregulated expression of auxin-responsive transgenes. Two different tightly regulated (i.e., very low expression in the absence of auxin treatment and very high expression after exogenous auxin treatment) auxin-responsive promoters were used to drive the expression of both a ?-glucuronidase (GUS) reporter gene and a hygromycin phosphotransferase (HPH)?selectable marker gene. This screen yielded several mutants, and five of the mutations (axe1-1 to axe1-5) mapped to the same locus on chromosome 5. A map-based cloning approach was used to locate the axe1 mutations in an Arabidopsis RPD3-like histone deacetylase gene, referred to as HDA6. The axe1 mutant plants displayed increased expression of the GUS and HPH transgenes in the absence of auxin treatment and increased auxin-inducible expression of the transgenes compared with nonmutant control plants. None of a variety of endogenous, natural auxin-inducible genes in the mutant plants were upregulated like the transgenes, however. Results of treatment with the DNA methylation inhibitor 5-aza-2'-deoxycytidine suggest that the axe1 mutations affect transgene silencing; however, histone deacetylase inhibitors had no affect on transgene silencing in mutant or control plants. The specific effect of AtHDA6 mutations on the auxin-responsive transgenes implicates this RPD3-like histone deacetylase as playing a role in transgene silencing. Furthermore, the effect of AtHDA6 on transgene silencing may be independent of its histone deacetylase activity. *
Project description:Maintenance of the root-meristem is determined by polar auxin transport (PAT) and asymmetric cell division (ACD). We find that flavonoids scutellarin and scutellarein, which both have 6-hydroxyl group that differs in its structure from all known-flavonoid PAT inhibitors, promote PAT and ACD in Arabidopsis thaliana root tip, and increase root length. We used microarrays to detail the global programme of gene expression under scutellarin and mock (DMSO) treatment and identified distinct classes of genes regulated by scutellarin.
Project description:We performed an analysis of transcriptomic responses to auxin within four distinct tissues of the Arabidopsis thaliana root. This high-resolution dataset shows how different cell types are predisposed to react to auxin with discrete transcriptional responses. The sensitivity provided by the analysis lies in the ability to detect cell-type specific responses diluted in organ-level analyses. This dataset provides a novel resource to examine how auxin, a widespread signal in plant development, influences differentiation and patterning in the plant through tissue-specific transcriptional regulation.