Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of Arabidopsis root developmental zones after treatment with salt

ABSTRACT: To gain a genome-scale understanding of the role that developmental processes play in regulating stimulus response, we examined the effect of salt stress on gene expression along the longitudinal axis of the root. Since roots grow from stem cells located near the tip, the position of cells along the longitudinal axis can be used as a proxy for developmental time, with distance from the root tip correlating with increased differentiation. To estimate the role developmental stage plays in regulating salt response, roots were dissected into four longitudinal zones (LZ data set) after transfer to standard or salt media and transcriptionally profiled. Cells are amazingly adept at integrating both external and internal cues to regulate transcriptional states. While internal processes such as differentiation and cell-type specification are generally understood to have an important impact on gene expression, very little is known about how cells utilize these developmental cues to regulate responses to external stimuli. Here we use the response to a well characterized environmental stress, high salinity, to obtain a global view of the role that cell identity plays in guiding transcriptional responses in the root of Arabidopsis. Our analysis is based on three microarray data sets we have generated that explore transcriptional changes spatially among 6 cell layers and 4 longitudinal regions or temporally along 5 time points after salt treatment. We show that the majority of the response to salt stress is cell-type specific resulting in the differential regulation of unique biological functions in subsets of cell layers. To understand the regulatory mechanisms controlling these responses we have analyzed cis-element enrichment in the promoters of salt responsive genes and demonstrate that known stress regulatory elements likely control responses to salt occurring in multiple cell types. Despite the extensive shift in transcriptional state that salt stress elicits, we are able to identify several biological processes that consistently define each cell layer and find that transcriptional regulators of cell-identity tend to exhibit robust cell-type specific expression. Finally, using mutants that disrupt cell-type specification in the epidermis, we reveal cell autonomous and non-autonomous effects when cell identity is altered. Together, these data elucidate a novel intersection between physiology and development and expand our understanding of how transcriptional states are regulated in a multi-cellular context. Experiment Overall Design: Roots were grown under standard conditions for 5 days then transfered to standard media or media supplemented with 140 mM NaCl. One hour after transferring seedlings, roots were cut into 4 regions using a razor blade. The first cut was made ~150 Âµm from the root tip at the point where the shape of the root transitions from conical to cylindrical (Zone 1). The second cut was made ~200 Âµm above the first cut, at the point were the root becomes less optically dense, which marks the approximate end of the meristematic zone (Zone 2). The third cut was made ~200-300 Âµm above the second cut, just below the region where root hairs begin to emerge (Zone 3). The fourth cut was made ~1 mm above the third cut (Zone 4).

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Jose Ramon Dinneny

PROVIDER: E-GEOD-7639 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Cell identity mediates the response of Arabidopsis roots to abiotic stress.

Dinneny José R JR Long Terri A TA Wang Jean Y JY Jung Jee W JW Mace Daniel D Pointer Solomon S Barron Christa C Brady Siobhan M SM Schiefelbein John J Benfey Philip N PN

Science (New York, N.Y.) 20080424 5878

Little is known about the way developmental cues affect how cells interpret their environment. We characterized the transcriptional response to high salinity of different cell layers and developmental stages of the Arabidopsis root and found that transcriptional responses are highly constrained by developmental parameters. These transcriptional changes lead to the differential regulation of specific biological functions in subsets of cell layers, several of which correspond to observable physiol ...[more]

PMID: 18436742

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Project description:To gain a genome-scale understanding of the role that developmental processes play in regulating stimulus response, we examined the effect of -Fe stress on gene expression along the longitudinal axis of the root. Since roots grow from stem cells located near the tip, the position of cells along the longitudinal axis can be used as a proxy for developmental time, with distance from the root tip correlating with increased differentiation. To estimate the role developmental stage plays in regulating salt response, roots were dissected into four longitudinal zones (LZ data set) after transfer to standard or -Fe media and transcriptionally profiled. Little is known about how developmental cues affect the way cells interpret their environment. Here we characterize the transcriptional response of different cell layers and developmental stages of the Arabidopsis root to high salinity and find that transcriptional responses are highly constrained by developmental parameters. These transcriptional changes lead to the differential regulation of specific biological functions in subsets of cell-layers, several of which correspond to observable physiological changes. We show that known stress pathways primarily control semi-ubiquitous responses and use mutants that disrupt epidermal patterning to reveal cell-layer specific and inter-cell-layer effects. By performing a similar analysis using iron-deprivation we identify common cell-type specific stress responses and environment-independent biological functions that define each cell type. Experiment Overall Design: Roots were grown under standard conditions for 5 days then transfered to standard media or iron deficient (-Fe) conditions (0.3mM Ferrozine in MS media containing no ferrous sulfate). 24 hours after transferring seedlings, roots were cut into 4 regions using a razor blade. The first cut was made ~150 Âµm from the root tip at the point where the shape of the root transitions from conical to cylindrical (Zone 1). The second cut was made ~200 Âµm above the first cut, at the point were the root becomes less optically dense, which marks the approximate end of the meristematic zone (Zone 2). The third cut was made ~200-300 Âµm above the second cut, just below the region where root hairs begin to emerge (Zone 3). The fourth cut was made ~1 mm above the third cut (Zone 4).

Project description:We performed an expression analysis of the response of seedling root tips to 1 hour of treatment with 140mM NaCl using mutants defective in root hair patterning. Cells are amazingly adept at integrating both external and internal cues to regulate transcriptional states. While internal processes such as differentiation and cell-type specification are generally understood to have an important impact on gene expression, very little is known about how cells utilize these developmental cues to regulate responses to external stimuli. Here we use the response to a well characterized environmental stress, high salinity, to obtain a global view of the role that cell identity plays in guiding transcriptional responses in the root of Arabidopsis. Our analysis is based on three microarray data sets we have generated that explore transcriptional changes spatially among 6 cell layers and 4 longitudinal regions or temporally along 5 time points after salt treatment. We show that the majority of the response to salt stress is cell-type specific resulting in the differential regulation of unique biological functions in subsets of cell layers. To understand the regulatory mechanisms controlling these responses we have analyzed cis-element enrichment in the promoters of salt responsive genes and demonstrate that known stress regulatory elements likely control responses to salt occurring in multiple cell types. Despite the extensive shift in transcriptional state that salt stress elicits, we are able to identify several biological processes that consistently define each cell layer and find that transcriptional regulators of cell-identity tend to exhibit robust cell-type specific expression. Finally, using mutants that disrupt cell-type specification in the epidermis, we reveal cell autonomous and non-autonomous effects when cell identity is altered. Together, these data elucidate a novel intersection between physiology and development and expand our understanding of how transcriptional states are regulated in a multi-cellular context. Experiment Overall Design: Seedlings were grown for 5 days before being transferred to standard media or media supplemented with 140mM NaCl. One hour after transfer, a razor blade was used to cut the root ~5 mm above the root tip. Approximately 30 roots were pooled per replicate. Two biological replicates were performed per genotype, per condition.

Project description:To gain a genome-scale understanding of the role that developmental processes play in regulating stimulus response, we examined the effect of salt stress on gene expression along the longitudinal axis of the root. Since roots grow from stem cells located near the tip, the position of cells along the longitudinal axis can be used as a proxy for developmental time, with distance from the root tip correlating with increased differentiation. To estimate the role developmental stage plays in regulating salt response, roots were dissected into four longitudinal zones (LZ data set) after transfer to standard or salt media and transcriptionally profiled. Cells are amazingly adept at integrating both external and internal cues to regulate transcriptional states. While internal processes such as differentiation and cell-type specification are generally understood to have an important impact on gene expression, very little is known about how cells utilize these developmental cues to regulate responses to external stimuli. Here we use the response to a well characterized environmental stress, high salinity, to obtain a global view of the role that cell identity plays in guiding transcriptional responses in the root of Arabidopsis. Our analysis is based on three microarray data sets we have generated that explore transcriptional changes spatially among 6 cell layers and 4 longitudinal regions or temporally along 5 time points after salt treatment. We show that the majority of the response to salt stress is cell-type specific resulting in the differential regulation of unique biological functions in subsets of cell layers. To understand the regulatory mechanisms controlling these responses we have analyzed cis-element enrichment in the promoters of salt responsive genes and demonstrate that known stress regulatory elements likely control responses to salt occurring in multiple cell types. Despite the extensive shift in transcriptional state that salt stress elicits, we are able to identify several biological processes that consistently define each cell layer and find that transcriptional regulators of cell-identity tend to exhibit robust cell-type specific expression. Finally, using mutants that disrupt cell-type specification in the epidermis, we reveal cell autonomous and non-autonomous effects when cell identity is altered. Together, these data elucidate a novel intersection between physiology and development and expand our understanding of how transcriptional states are regulated in a multi-cellular context. Keywords: Tissue specific analysis

Project description:Previous work showed that the maize primary root adapts to low water potential (-1.6 MPa) by maintaining longitudinal expansion in the apical 3 mm (region 1), whereas in the adjacent 4 mm (region 2) longitudinal expansion reaches a maximum in well-watered roots but is progressively inhibited at low water potential. To identify mechanisms that determine these responses to low water potential, transcript expression was profiled in these regions of water-stressed and well-watered roots. In addition, comparison between region 2 of water-stressed roots and the zone of growth deceleration in well-watered roots (region 3) distinguished stress-responsive genes in region 2 from those involved in cell maturation. Responses of gene expression to water stress in regions 1 and 2 were largely distinct. The largest functional categories of differentially expressed transcripts were reactive oxygen species and carbon metabolism in region 1, and membrane transport in region 2. Transcripts controlling sucrose hydrolysis distinguished well-watered and water-stressed states (invertase vs. sucrose synthase), and changes in expression of transcripts for starch synthesis indicated further alteration in carbon metabolism under water deficit. A role for inositols in the stress response was suggested, as was control of proline metabolism. Increased expression of transcripts for wall-loosening proteins in region 1, and for elements of ABA and ethylene signaling were also indicated in the response to water deficit. The analysis indicates that fundamentally different signaling and metabolic response mechanisms are involved in the response to water stress in different regions of the maize primary root elongation zone. Keywords: water stress response, root growth Three pair-wise comparisons were made of transcripts from water-stressed and well-watered tissues in the different root tip regions. In the first comparison (C1), transcripts from region 1 of water-stressed seedlings were compared with those from region 1 of well-watered seedlings. The second comparison (C2) was made between transcripts from region 2 of the two treatments. We expected a larger number of genes to be differentially expressed in region 2 because its elongation rate decreased greatly under water-stressed compared with well-watered conditions. To prioritize the differentially expressed genes revealed in this comparison, a distinction was made between those genes that are associated with growth inhibition in region 2 specifically as a response to water stress, and those genes that are involved in root cell maturation whether under stress or control conditions. A hypothetical example of the former might be genes involved in auxin response since water stress can increase maize root auxin content [8] and application of exogenous auxin can shorten the root growth zone [9]. An example of the latter might involve genes for secondary wall synthesis, e.g., [10]. To experimentally make this distinction a third pair-wise comparison (C2/3) was included to compare expression of genes between water-stressed region 2 and well-watered region 3 as these are both regions of cell maturation. Genes differentially expressed in both C2 and C2/3 are more likely to cause growth inhibition at low water potential and are not likely to be part of the maturation program itself, whereas genes differentially expressed only in C2 are more likely related to maturation. Four biological replicates were included each with dye-swap. The maize oligonucleotide array comes in two slides, A and B. Thus for each of the three comparisons made there were 16 slides (4 biological reps, 2 for dye-swap, 2 parts to an array).

Project description:Cell-type specific transcriptional profiles were generated by FACS (Fluorescence Activated Cell Sorting) sorting of roots that express cell-type specific GFP-reporters. Six different GFP-reporter lines were utilized allowing us to obtain transcriptional profiles for cells in all radial zones of the root. FACS cell populations were isolated from roots grown under standard conditions or roots that had been transfered to media supplemented with 140 mM NaCl for 1 hour. Cells are amazingly adept at integrating both external and internal cues to regulate transcriptional states. While internal processes such as differentiation and cell-type specification are generally understood to have an important impact on gene expression, very little is known about how cells utilize these developmental cues to regulate responses to external stimuli. Here we use the response to a well characterized environmental stress, high salinity, to obtain a global view of the role that cell identity plays in guiding transcriptional responses in the root of Arabidopsis. Our analysis is based on three microarray data sets we have generated that explore transcriptional changes spatially among 6 cell layers and 4 longitudinal regions or temporally along 5 time points after salt treatment. We show that the majority of the response to salt stress is cell-type specific resulting in the differential regulation of unique biological functions in subsets of cell layers. To understand the regulatory mechanisms controlling these responses we have analyzed cis-element enrichment in the promoters of salt responsive genes and demonstrate that known stress regulatory elements likely control responses to salt occurring in multiple cell types. Despite the extensive shift in transcriptional state that salt stress elicits, we are able to identify several biological processes that consistently define each cell layer and find that transcriptional regulators of cell-identity tend to exhibit robust cell-type specific expression. Finally, using mutants that disrupt cell-type specification in the epidermis, we reveal cell autonomous and non-autonomous effects when cell identity is altered. Together, these data elucidate a novel intersection between physiology and development and expand our understanding of how transcriptional states are regulated in a multi-cellular context. Experiment Overall Design: To gain a genome-scale understanding of the role that developmental processes play in regulating stimulus response, we examined the effect of salt stress on gene expression along the radial axis of the root. Cell identity is the main variable that changes along the radial axis with the epidermis representing the outermost tissue layer and the stele representing the inner most layer. 6 different GFP reporter lines were used to isolate specific populations of cells from the Arabidopsis root using FACS sorting of protoplasted cells. GFP-reporter lines were grown under standard conditions before protoplasting and sorting or they were transfered to media supplemented with 140mM NaCl for 1 hour before hand.

Dataset Information

Transcription profiling of Arabidopsis root developmental zones after treatment with salt

Publications

Cell identity mediates the response of Arabidopsis roots to abiotic stress.

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