40 QC single cells multiplexed using the CEL-Seq protocol Overall design: 40 cells from the QC
Quantification of cell identity from single-cell gene expression profiles.
Age, Subject
View SamplesLeaf development has been monitored chiefly by following anatomical markers. Analysis of transcriptome dynamics during leaf maturation revealed multiple expression patterns that rise or fall with age or that display age specific peaks. These were used to formulate a digital differentiation index (DDI), based on a set of selected markers with informative expression during leaf ontogeny. The leaf-based DDI reliably predicted the developmental state of leaf samples from diverse sources and was independent of mitotic cell division transcripts or propensity of the specific cell type. When calibrated by informative root markers, the same algorithm accurately diagnosed dissected root samples. We used the DDI to characterize plants with reduced activities of multiple CINCINNATA (CIN)-TCP growth regulators. These plants had giant curled leaves made up of small cells with abnormal shape, low DDI scores and low expression of mitosis markers, depicting the primary role of CIN-TCPs as promoters of differentiation. Delayed activity of several CIN-TCPs resulted in abnormally large but flat leaves with regular cells. The application of DDI has therefore portrayed the CIN-TCPs as heterochronic regulators that permit the development of a flexible and robust leaf form through an ordered and protracted maturation schedule.
A protracted and dynamic maturation schedule underlies Arabidopsis leaf development.
No sample metadata fields
View SamplesLeaf development has been monitored chiefly by following anatomical markers. Analysis of transcriptome dynamics during leaf maturation revealed multiple expression patterns that rise or fall with age or that display age specific peaks. These were used to formulate a digital differentiation index (DDI), based on a set of selected markers with informative expression during leaf ontogeny. The leaf-based DDI reliably predicted the developmental state of leaf samples from diverse sources and was independent of mitotic cell division transcripts or propensity of the specific cell type. To calibrate and test the DDI a series of Arabidopsis shoot development was used (Efroni et al, 2008)
A protracted and dynamic maturation schedule underlies Arabidopsis leaf development.
No sample metadata fields
View SamplesThe Arabidopsis quiescent center (QC) is a small group of cells with low mitotic activity located at the center of the root stem cell niche. Its transcriptional profile was previously analyzed using two repeats of cells FACS isolated using the WOX5 marker.
Quantification of cell identity from single-cell gene expression profiles.
Specimen part
View SamplesFloral organ identities are specified by few transcription factors which act as master regulators. Subsequently, specification of organ axes programs the distribution of distinct tissue types within the organs that themselves develop unique identities. The C-class, AGAMOUS-clade MADS box genes are primary promoters of the gynoecium which is divided into a distal style and a subtending ovary along the apical-basal axis. We show that members of a clade of B3-domain transcription factors, NGATHA1 to NGA4 (NGA1-4), are expressed distally in all lateral organs, and all four have a redundant and essential role in style development. Loss of all four genes results in gynoecia where style is replaced by valve-like projections and a reduction in style-specific SHATTERPROOF1 (SHP1) expression. In agreement, floral misexpression of NGA1 promotes ectopic style and SHP1 expression. STYLISH1, an auxin biosynthesis inducer, conditionally activated NGA genes, which in turn, promoted distal expression of other STY genes in a putative positive feed back loop. Inhibited auxin transport or lack of YABBY1 gene activities resulted in a basally expanded style domain and broader expression of NGA genes. We speculate that early gynoecium factors delimit NGA gene response to an auxin-based signal, elicited by STY gene activity, to restrict the activation of style program to a late and distal carpel domain.
The NGATHA distal organ development genes are essential for style specification in Arabidopsis.
Age
View SamplesLeaves 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.
Active suppression of a leaf meristem orchestrates determinate leaf growth.
Specimen part
View SamplesHeat acclimation (AC) allows its faster re-induction following its decline. Constitutively preserved euchromatin state in hsp70 promoter during acclimation decline/regain pushed forward the hypothesis that acclimation decline is a period of dormant memory involving molecular program including epigenetic controlled transcriptional regulation leading to heat acclimation mediated cytoprotective memory.
Heat acclimation memory: do the kinetics of the deacclimated transcriptome predispose to rapid reacclimation and cytoprotection?
Specimen part
View SamplesIn seed plants, leaves are born on radial shoots but unlike shoots they are determinate dorsiventral organs made of flat lamina. YABBY genes are found only in seed plants and in all cases studied, are expressed primarily in lateral organs and in a polar manner. Despite their simple expression, Arabidopsis plants lacking all YABBY gene activities have a wide range of morphological defects in all lateral organs as well as the shoot apical meristem. Here we show that leaves lacking all YABBY activities are initiated as dorsiventral appendages but fail to properly activate lamina programs. In particular, the activation of most CIN-TCPs does not commence, SAM-specific programs are reactivated, and a marginal leaf domain is not established. Altered distribution of auxin signalling and the auxin efflux carrier PIN1, highly reduced venation, initiation of multiple cotyledons, and gradual loss of the SAM accompany these defects. We suggest that YABBY functions were recruited to mould modified shoot systems into flat plant appendages by translating organ polarity into lamina specific programs that include marginal auxin flow and activation a maturation schedule directing determinate growth.
Differentiating Arabidopsis shoots from leaves by combined YABBY activities.
Specimen part
View SamplesWe 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.
A map of cell type-specific auxin responses.
Specimen part, Treatment
View SamplesWe have analyzed the effects of IL-27 signaling in dendritic cells (DCs) in the activation and polarization of effector and regulatory T cells, and the development of experimental autoimmune encephalomyelitis, an experimental model of multiple sclerosis.
IL-27 acts on DCs to suppress the T cell response and autoimmunity by inducing expression of the immunoregulatory molecule CD39.
Age, Specimen part, Treatment
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