Project description:Background: The carpel margin meristem is a vital multi-potent structure located in the medial domain of the Arabidopsis thaliana gynoecium, the female floral reproductive organ. The carpel margin meristem generates ovules that upon fertilization become seeds. The molecular mechanisms that specify this meristematic region and regulate its organogenic potential are poorly understood. Here, we present an analysis of the transcriptional profile of the medial domain of the Arabidopsis gynoecium highlighting the developmental stages that immediately proceed ovule initiation, the earliest stages of seed development. Results: Using a floral synchronization system and a SHATTERPROOF2 domain-specific reporter construct, paired with fluorescence-activated cell sorting, we assayed the transcriptome of the gynoecial medial domain with temporal and spatial precision. Our analysis reveals a set of genes that are differentially-expressed within the SHATTERPROOF2 expression domain that marks portions of the developing medial domain. Many members of this gene set have been shown previously to function during the development of medial domain-derived structures, including the ovules, thus validating our approach. Other uncharacterized members of this gene set, including a set of differentially-expressed cis-natural antisense transcripts, are potential novel regulators of medial domain development and candidates for future functional studies. Several members of the REM family of transcriptional regulators were enriched in the SHP2-expressing cell population including a previously unrecognized REM family member (At5g60142). Analysis of the abundance of specific transcriptional isoforms identified genes that may exhibit “isoform switching” behavior during gynoecial development. Conclusions: This data set provides genome-wide transcriptional insight into the development of the gynoecial medial domain that contains the carpel margin meristem, an important reproductive structure that gives rise to the ovules in Arabidopsis thaliana.
Project description:Background: The carpel margin meristem is a vital multi-potent structure located in the medial domain of the Arabidopsis thaliana gynoecium, the female floral reproductive organ. The carpel margin meristem generates ovules that upon fertilization become seeds. The molecular mechanisms that specify this meristematic region and regulate its organogenic potential are poorly understood. Here, we present an analysis of the transcriptional profile of the medial domain of the Arabidopsis gynoecium highlighting the developmental stages that immediately proceed ovule initiation, the earliest stages of seed development. Results: Using a floral synchronization system and a SHATTERPROOF2 domain-specific reporter construct, paired with fluorescence-activated cell sorting, we assayed the transcriptome of the gynoecial medial domain with temporal and spatial precision. Our analysis reveals a set of genes that are differentially-expressed within the SHATTERPROOF2 expression domain that marks portions of the developing medial domain. Many members of this gene set have been shown previously to function during the development of medial domain-derived structures, including the ovules, thus validating our approach. Other uncharacterized members of this gene set, including a set of differentially-expressed cis-natural antisense transcripts, are potential novel regulators of medial domain development and candidates for future functional studies. Several members of the REM family of transcriptional regulators were enriched in the SHP2-expressing cell population including a previously unrecognized REM family member (At5g60142). Analysis of the abundance of specific transcriptional isoforms identified genes that may exhibit âisoform switchingâ behavior during gynoecial development. Conclusions: This data set provides genome-wide transcriptional insight into the development of the gynoecial medial domain that contains the carpel margin meristem, an important reproductive structure that gives rise to the ovules in Arabidopsis thaliana. Four samples (YFP-positive, YFP-negative, all-sorted, and non-sorted). Four biological replicates of each sample (except YFP-positive, collected in triplicated). Strand-specific libraries were sequenced (single-end) in two lanes of a HiSeq 2500 Illumina flow cell (each lane was later analyzed as a technical replicate).
Project description:We are interested in examining the transcriptional hierarchies that are required for proper formation and function of the carpel margin meristem in Arabidopsis thaliana. The carpel margin meristem (CMM) gives rise to the ovule primorida (which begin to form around flower stage 8). We know that the loss of the seuss-3 (seu-3) and aintegumenta-1(ant-1) separately leads to a mild disruption of ovule formation, while the loss of both causes a complete loss of ovule formation. In this study we wanted to examine expression levels changed between each single mutant and the double mutant. We dissected out stage 8-10 carpel of each of the four genotypes (seu-3, ant-1, Col-0, seu-3 ant-1) pooling 15-25 carpels into one biological replicate. Then using 16 ATH1 arrays we hybridized, amplified and labeled cDNA to 16 arrays (4 replicates for each genotype). We then analyzed our data to reveal transcripts that went down in the double compared to either single mutant, and transcripts that went down more than additively in the double mutant compared to added level of the decrease of the single mutant levels.
Project description:We are interested in examining the transcriptional hierarchies that are required for proper formation and function of the carpel margin meristem in Arabidopsis thaliana. The carpel margin meristem (CMM) gives rise to the ovule primorida (which begin to form around flower stage 8). We know that the loss of the seuss-3 (seu-3) and aintegumenta-1(ant-1) separately leads to a mild disruption of ovule formation, while the loss of both causes a complete loss of ovule formation. In this study we wanted to examine expression levels changed between each single mutant and the double mutant. We dissected out stage 8-10 carpel of each of the four genotypes (seu-3, ant-1, Col-0, seu-3 ant-1) pooling 15-25 carpels into one biological replicate. Then using 16 ATH1 arrays we hybridized, amplified and labeled cDNA to 16 arrays (4 replicates for each genotype). We then analyzed our data to reveal transcripts that went down in the double compared to either single mutant, and transcripts that went down more than additively in the double mutant compared to added level of the decrease of the single mutant levels. 16 arrays: 4 seuss-3, 4 aintegumenta-1, 4 Col-0, 4 seuss-3 aintegumenta-1. Each biological replicate was a sample of 15-25 pooled stage 8-10 carpels manually dissected by hand.
Project description:Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly to suppress activity of a leaf margin meristem in Arabidopsis thaliana, and that their absence confers persistent marginal growth of leaves, cotyledons and floral organs. The marginal meristem is activated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, but other margin elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic from an ancestral shoot system from which seed plant leaves evolved.
Project description:One of the key innovations of the flowering plants is their female reproductive organ, the carpel. Here we show that a mechanism controlling carpel margin development in the model flowering plant Arabidopsis thaliana was recruited from light-regulated processes. This recruitment followed the loss from the basic Helix-Loop-Helix transcription factor SPATULA (SPT) of a domain previously responsible for its negative regulation by phytochrome. We propose that the loss of this domain was a prerequisite for the light-independent expression in female reproductive tissues of a genetic module that also promotes shade avoidance responses in vegetative organs. Striking evidence for this proposition is provided by the restoration of wild type carpel development to spt mutants by low red/far-red light ratios, simulating vegetation shade, which we show to occur via PHYB, PIF4 and PIF5. Our data illustrate the potential of modular evolutionary events to generate rapid morphological change, and thereby provide a molecular basis for neo-Darwinian theories that describe this non-gradualist phenomenon. Furthermore, the effects shown here of light quality perception on carpel development lead us to speculate on the potential role of light-regulated mechanisms in plant organs that, like the carpel, form within the shade of surrounding tissues.
Project description:This model is from the article:
The influence of cytokinin-auxin cross-regulation on cell-fate determination in Arabidopsis thaliana root development
Muraro D, Byrne H, King J, Voss U, Kieber J, Bennett M.
J Theor Biol.2011 Aug 21;283(1):152-67.
PMID: 21640126,
Abstract:
Root growth and development in Arabidopsis thaliana are sustained by a specialised zone termed the meristem, which contains a population of dividing and differentiating cells that are functionally analogous to a stem cell niche in animals. The hormones auxin and cytokinin control meristem size antagonistically. Local accumulation of auxin promotes cell division and the initiation of a lateral root primordium. By contrast, high cytokinin concentrations disrupt the regular pattern of divisions that characterises lateral root development, and promote differentiation. The way in which the hormones interact is controlled by a genetic regulatory network. In this paper, we propose a deterministic mathematical model to describe this network and present model simulations that reproduce the experimentally observed effects of cytokinin on the expression of auxin regulated genes. We show how auxin response genes and auxin efflux transporters may be affected by the presence of cytokinin. We also analyse and compare the responses of the hormones auxin and cytokinin to changes in their supply with the responses obtained by genetic mutations of SHY2, which encodes a protein that plays a key role in balancing cytokinin and auxin regulation of meristem size. We show that although shy2 mutations can qualitatively reproduce the effect of varying auxin and cytokinin supply on their response genes, some elements of the network respond differently to changes in hormonal supply and to genetic mutations, implying a different, general response of the network. We conclude that an analysis based on the ratio between these two hormones may be misleading and that a mathematical model can serve as a useful tool for stimulate further experimental work by predicting the response of the network to changes in hormone levels and to other genetic mutations.
Project description:gnp07_regeneome_cuc2 - cuc2 - CUC2 is expressed in meristem. It permits to create organs boundaries. It is also expressed in leave margins. Is there a mecanism meristem like in leave margins? - To compare wt and cuc2 leaf margins. And compare teeth and hollow inside the arabidopsis leaf margin.