Project description:This SuperSeries is composed of the following subset Series:; GSE8739: Early gibberellin responses in Arabidopsis; GSE8741: DELLA protein direct targets in Arabidopsis Experiment Overall Design: Refer to individual Series
Project description:The aim is to identify early gibberellin responsive genes in a gibberellin deficient strain such as ga1-3. Such genes are likely regulated by DELLA proteins which are master gibberellin repressors. DELLA proteins are rapidly degraded after gibberellin treatment, but their direct target genes still need to be elucidated. Experiment Overall Design: A set of 4 biological replicates was generated for each treament. Arabidopsis seedlings were treated with water or 2 uM GA4 and whole shoots collected after 1h. A comparison of water vs. GA4 treated samples should render a list of early gibberellin responsive genes.
Project description:We combined transcriptomic profiling of auxin related mutants with genetic and biochemical approaches and live-cell imaging techniques of Arabidopsis roots to understand the role of auxin-driven gibberellin level changes during root development, particularly root cell elongation. We show that auxin negatively regulates the level of gibberellin in root elongation zone. Auxin signalling steers the expression of gibberellin deactivating enzymes - GIBBERELLIN 2-OXIDASES (GA2OX) exclusively in root elongation zone. Interestingly, GA2OX8 expression is high in tissues with elevated auxin levels, such as vasculature or stem cell niche, fitting with the observed effect of auxin on gibberellin level. Here we show that GA2OX enzymes are negative regulators of root cell elongation. Gibberellin decrease caused by GA2OX8 overexpression inhibits root cell elongation. In contrast, roots missing GA2OX genes elongate faster. These findings indicate that GA2OX8 enzymes represent an integration core of auxin and gibberellin signalling pathway in root elongation zone, vascular development and regulation of stem cell niche. Our results enhance understanding of complex mechanisms controlling root cell elongation.