Project description:Ovule development is a key process for plant reproduction that ensures correct seed production. Understanding the molecular mechanisms that control ovule formation will also provide new approaches to increase crop yield for breeding. Several molecular factors and plant hormones, including gibberellins, are involved in ovule initiation and development. Gibberellins control ovule development by the destabilization of DELLA proteins, whereas DELLA activity has been proved to act as a positive factor for ovule primordia emergence. But the molecular mechanism by which DELLA act remained unknown. Here we have proved that DELLA proteins control ovule initiation by the formation of a protein complex with the CUC2 transcription factor. The DELLA protein GAI requires CUC2 to promote ovule primordia formation, thus GAI would function by its direct protein-protein interaction with CUC2 in cells of the placenta that determine the boundary regions between ovules during pistil development. Analysis of GAI-CUC2 interaction and colocalization in placenta support this hypothesis. Moreover, molecular analysis of the loci at which GAI protein may act as transcriptional co-regulators in a CUC2-dependent manner identified a subset of target genes that would be regulated by the GAI-CUC2 complex and contribute to regulate ovule primordia emergence.
Project description:The aim of this study is to identify early DELLA protein-responsive genes using a Dexamethasone (DEX)-inducible system. Two transgenic lines were used: one induces the expression of a dominant, gibberellin non-responsive DELLA protein (rga-delta17); the other is a control line that carries the same vector, but lacks the rga-delta17 transgene. By comparing the gene expression changes in the line that expresses the rga-delta17 protein in the presence or absence of DEX it is possible to identify putative targets of DELLA proteins. An empty vector transgenic line was included in this study to identify genes that might be regulated by the DEX inducible system that are not dependent on the DELLA protein. Keywords: Dexamethasone treatment, gibberellin treatment, time course, transgene effect
Project description:rs09-09_della-dark - della-regulation in darkness versus light - Identification of DELLA-dependent downstream targets in darkness - Aim was to determine downstream target of DELLA proteins involved in skotomorphogenesis. Wt, ga1-3, ga1-3_rga_gai_rgl1_rgl2_rgl3 global seeds were sterilized, sown on MS agar plates then put for stratification for 3 days at 4°C. Plates were placed in growth cabinet at 22°C for 5 days in darkness or in continous light. Keywords: gene knock out
Project description:We previously showed that increased levels of the tomato DELLA protein PROCERA (PRO) promoted ABA responses in guard cells, including ABA-induced stomatal closure and gene expression. Thus we aimed to identifiy DELLA-regulated genes in guard cells in order to study the molecular mechanism by which DELLA promotes stomatal closure.
Project description:The hormones gibberellins (GA) control many aspects of plant growth and development thruough the whole life cycle of the plant. For instance, GA participate in the establishment of the skotomorphogenic developmental program that is triggered when seeds germinate in darkness, i.e. under the soil. Under these conditions seedlings appear etiolated and developmental features usually triggered by light are kept repressed. The GA signaling elements GAI and RGA have a major, partially redundant role in this process. These proteins belong to the DELLA family of transcriptional regulators and are destabilized by GA, acting as negative regulators of the pathway. In order to understand the molecular basis of the regulation of the skotomorphogenesis by GA, we sought to identify early target genes of the activity of GAI in etiolated seedlings. For that purpose we analyzed rapid, global changes in gene expression in response to a transient accummulation of a dominant version of GAI, gai-1, which is resistant to GA-induced destabilization.
Project description:The DELLA genes encode conserved master growth repressors in plants, and they are also known as ‘Green Revolution’ genes because of their pivotal role in modulating stature of the high-yielding wheat varieties, which were crucial for the success of the ‘Green Revolution’ in the 1960s. At the cellular level, DELLA proteins are nuclear-localized transcription regulators, which play a central role in controlling plant development in response to internal and environmental cues. Recent studies indicate that DELLAs regulate expression of target genes via direct protein-protein interaction of their C-terminal GRAS domain with hundreds of key transcription factors (TFs) and epigenetic regulators. However, the molecular mechanism of DELLA-mediated transcription reprogramming remains unclear. Here, by characterizing missense alleles of an Arabidopsis DELLA, REPRESSOR OF ga1-3 (RGA), we unveil a novel function of the PFYRE subdomain within its GRAS domain for binding to histone H2A via pulldown and co-IP assays. ChIP-Seq analysis further show that this activity is essential for RGA association with its target chromatin globally. Our results indicate that although DELLAs are recruited to target gene promoters by binding to TFs via its LHR1 subdomain, DELLA-H2A interaction via its PFYRE subdomain is necessary to stabilize the TF-DELLA-H2A complex at the target chromatin. This study provides new insight into the two distinct key modular functions in DELLA for its genome-wide transcription regulation in plants. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for RGA, rga-11 as well as the negative control sly1 dP and sly1 dQ.
Project description:The DELLA genes encode conserved master growth repressors in plants, and they are also known as ‘Green Revolution’ genes because of their pivotal role in modulating stature of the high-yielding wheat varieties, which were crucial for the success of the ‘Green Revolution’ in the 1960s. At the cellular level, DELLA proteins are nuclear-localized transcription regulators, which play a central role in controlling plant development in response to internal and environmental cues. Recent studies indicate that DELLAs regulate expression of target genes via direct protein-protein interaction of their C-terminal GRAS domain with hundreds of key transcription factors (TFs) and epigenetic regulators. However, the molecular mechanism of DELLA-mediated transcription reprogramming remains unclear. Here, by characterizing missense alleles of an Arabidopsis DELLA, REPRESSOR OF ga1-3 (RGA), we unveil a novel function of the PFYRE subdomain within its GRAS domain for binding to histone H2A via pulldown and co-IP assays. ChIP-Seq analysis further show that this activity is essential for RGA association with its target chromatin globally. Our results indicate that although DELLAs are recruited to target gene promoters by binding to TFs via its LHR1 subdomain, DELLA-H2A interaction via its PFYRE subdomain is necessary to stabilize the TF-DELLA-H2A complex at the target chromatin. This study provides new insight into the two distinct key modular functions in DELLA for its genome-wide transcription regulation in plants. The assay for transposase-accessible chromatin using sequencing (ATAC-seq) for RGA vs rga-11 and RGA treated with GA or mock.