Transcriptome changes 1h or 4h following DELLA stabilisation in microdissected fully proliferating Arabidopsis leaves
Gibberellins and DELLAs: central nodes in growth regulatory networks.
Specimen part, Treatment, Time
View SamplesThe number of cells in an organ is a major factor for the determination of organ size. However, genetic basis of cell number determination is not well understood. Three grandifolia-D (gra-D) mutants of Arabidopsis thaliana developed huge leaves containing two- to three-fold increased number of cells of the wild type. Tiling array and microarray analysis of gra-D mutants suggested that genes found in a lower part of chromosome 4 were upregulated, suggesting the occurrence of segmental chromosomal duplications in the gra-D mutants. These region contain positive regulators of cell proliferation such as AINTEGUMENTA (ANT) and cyclin genes such as CYCD3;1.
Impact of segmental chromosomal duplications on leaf size in the grandifolia-D mutants of Arabidopsis thaliana.
Specimen part
View SamplesThe number of cells in an organ is a major factor for the determination of organ size. However, genetic basis of cell number determination is not well understood. Three grandifolia-D (gra-D) mutants of Arabidopsis thaliana developed huge leaves containing two- to three-fold increased number of cells of the wild type. Tiling array and microarray analysis of gra-D mutants suggested that genes found in a lower part of chromosome 4 were upregulated, suggesting the occurrence of segmental chromosomal duplications in the gra-D mutants. These region contain positive regulators of cell proliferation such as AINTEGUMENTA (ANT) and cyclin genes such as CYCD3;1.
Impact of segmental chromosomal duplications on leaf size in the grandifolia-D mutants of Arabidopsis thaliana.
Specimen part
View SamplesThe Growth Regulating Factors (GRFs) are plant specific transcription factors. They form complexes with GRF Interacting Factors (GIFs), a small family of transcriptional co-activators. In Arabidopsis thaliana, seven out of the nine GRFs are regulated by microRNA miR396. A detailed analysis of GRF3 revealed that a modified transgene, insensitive to the regulation of miR396, causes a strong increase in the number of cells in leaves, while an additional increase of GIF1 expression further enhances the number of cells synergistically. Genome-wide transcript profiling revealed that simultaneous increase of GRF3 and GIF1 levels causes additional effects in gene expression compared to either of the transgenes alone. We observed that GIF1 interacts in vivo with GRF3, as well as chromatin remodeling complexes, providing a mechanistic explanation for the additional activities of a GRF3-GIF1 complex. Interestingly, we found that the GRF system also regulates leaf longevity. Genetic and molecular analysis revealed that the functions of GRFs in leaf size and senescence can be uncoupled, demonstrating that the GRFs control different stages of leaf development. The results provide new insights into the functions of a complex regulatory network composed of microRNAs, transcription factors, and co-transcription factors.
Post-transcriptional control of GRF transcription factors by microRNA miR396 and GIF co-activator affects leaf size and longevity.
Specimen part
View SamplesAnalysis of the gene expression profile of the atx1 mutant of Arabidopsis thaliana compared to the wild-type, using apices tissue of in in vitro plants and Affymetrix ATH1 chips.
ARABIDOPSIS TRITHORAX1 dynamically regulates FLOWERING LOCUS C activation via histone 3 lysine 4 trimethylation.
Age, Specimen part
View SamplesThe transcriptional response of Arabidopsis thaliana cell suspensions following treatment with the stress hormone methyl jasmonate (MeJA) was monitored over time 16 hours after subcultivation. Three time points were included: 30 minutes, 2 hours and 6 hours after elicitation with 50µm MeJA or DMSO as a control.
Mapping methyl jasmonate-mediated transcriptional reprogramming of metabolism and cell cycle progression in cultured Arabidopsis cells.
Compound, Time
View SamplesDrought is an important environmental factor affecting plant growth and biomass production. Despite this importance little is known on the molecular mechanisms regulating plant growth under water limiting conditions. The main goal of this work was to investigate, using a combination of growth and molecular profiling techniques, how stress arrests CELl proliferation in Arabidopsis thaliana leaves upon osmotic stress imposition.
Pause-and-stop: the effects of osmotic stress on cell proliferation during early leaf development in Arabidopsis and a role for ethylene signaling in cell cycle arrest.
Specimen part
View SamplesDrought is an important environmental factor affecting plant growth and biomass production. Despite this importance, little is known on the molecular mechanisms regulating plant growth under water limiting conditions. The main goal of this work was to investigate, using a combination of growth and molecular profiling techniques, how Arabidopsis thaliana leaves adapt their growth to prolonged mild osmotic stress. Fully proliferating, expanding and mature leaves were harvested from plants grown on plates without (control) or with 25mM mannitol (osmotic stress) and compared to seedlings at stage 1.03.
Developmental stage specificity and the role of mitochondrial metabolism in the response of Arabidopsis leaves to prolonged mild osmotic stress.
Specimen part
View SamplesThe final size of plant organs such as leaves is tightly controlled by environmental and genetic factors that must spatially and temporally coordinate cell expansion and cell cycle activity. However this regulation of organ growth is still poorly understood. The aim of this study is to gain more insight in the genetic control of leaf size in Arabidopsis by performing a comparative analysis of transgenic lines that produce larger leaves under standardized environmental conditions. To this end, we selected five genes, belonging to different functional classes, that all positively affect leaf size when over-expressed: AVP1, GRF5, JAW, BRI1 and GA20OX1. We show that the increase in leaf area in these lines depends on leaf position and growth conditions and that all five lines affect leaf size differently. However, in all cases an increase in cell number is, entirely or predominantly, responsible for the leaf size enlargement. By means of analyses of hormone levels, transcriptome and metabolome we provide deeper insight in the molecular basis of the growth phenotype for the individual lines. A comparative analysis between them indicates that enhanced organ growth is governed by different, seemingly independent pathways. The analysis of transgenic lines simultaneously over-expressing two growth-enhancing genes further supports the concept that multiple pathways independently converge on organ size control in Arabidopsis.
Increased leaf size: different means to an end.
Specimen part
View SamplesLateral root initiation was used as a model system to study the mechanisms behind auxin-induced cell division. Genome-wide transcriptional changes were monitored during the early steps of lateral root initiation. Inclusion of the dominant auxin signaling mutant solitary root1 (slr1) identified genes involved in lateral root initiation that act downstream of the AUX/IAA signaling pathway. Interestingly, key components of the cell cycle machinery were strongly defective in slr1, suggesting a direct link between AUX/IAA signaling and core cell cycle regulation. However, induction of the cell cycle in the mutant background by overexpression of the D-type cyclin (CYCD3;1) was able to trigger complete rounds of cell division in the pericycle that did not result in lateral root formation. Therefore, lateral root initiation can only take place when cell cycle activation is accompanied by cell fate respecification of pericycle cells. The microarray data also yielded evidence for the existence of both negative and positive feedback mechanisms that regulate auxin homeostasis and signal transduction in the pericycle, thereby fine-tuning the process of lateral root initiation.
Cell cycle progression in the pericycle is not sufficient for SOLITARY ROOT/IAA14-mediated lateral root initiation in Arabidopsis thaliana.
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