Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of Arabidopsis root cell-types after iron deficiency (-Fe) treatment

ABSTRACT: Cell-type specific transcriptional profiles were generated by FACS (Fluorescence Activated Cell Sorting) sorting of roots that express cell-type specific GFP-reporters. Five 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 -Fe media for 24 hours. 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: 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 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. 5 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 exposed to iron deficient (-Fe) conditions (0.3mM Ferrozine in MS media containing no ferrous sulfate) for 24 hours before hand.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Terri Anita Long

PROVIDER: E-GEOD-10501 | 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:Transcriptional profile of whole roots of wild-type and pye-1 mutants exposed to 24 hours -Fe were generated Global population increases and climate change underscore the need for better comprehension of how plants acquire and process nutrients such as iron. A systems biology approach was taken to elucidate novel regulatory mechanisms involved in plant responses to iron deficiency (-Fe). Using cell-type specific transcriptional profiling we identified a pericycle-specific iron deficiency response, and a previously uncharacterized transcription factor, POPEYE (PYE), that plays an important role in this response. Functional analysis of PYE suggests that it positively regulates growth and development under iron deficient conditions. ChIP-on-chip analysis and transcriptional profiling reveal that PYE helps maintain iron homeostasis by directly and indirectly regulating the expression of ferric reductases, metal ion transporters, iron storage proteins, and other key iron homeostasis genes. In addition to PYE, we also identified a second protein BRUTUS (BTS), which appears to negatively regulate the response to iron deficiency. BTS is a unique putative E3 ligase protein, with metal ion binding and DNA binding domains. PYE and BTS are tightly co-regulated and physically interact with PYE paralogs, one of which is thought to positively regulate expression of genes involved in iron homeostasis. We propose that iron content is sensed within the pericycle where PYE, perhaps in conjunction with BTS and other regulatory proteins, is then activated to control a regulatory network involved in maintaining proper iron distribution in plants. Keywords: Expression analysis To determine how loss of PYE expression affects the transcriptional profile of whole roots, pye-1 mutants and wild-type seeds were germinated under standard growth conditions then transferred to standard media (control, MS media) or iron deficient media (-Fe, 0.3mM Ferrozine in MS media containing no ferrous sulfate). After 24 hours of exposure to +Fe or -Fe whole roots were collected and analyzed.

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 cell-types after iron deficiency (-Fe) treatment

Publications

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

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