Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Expression data from poplar roots under nitrogen limitation

ABSTRACT: We study the effect of nitrogen limitation on the growth and development of poplar roots. We used microarrays to detail the global program of gene expression underlying morphological and developmental changes driven by low nitrogen in the growth media. We report the effect of nitrogen limitation on the growth and development of poplar roots. Low nitrogen concentration led to increased root elongation followed by lateral root proliferation and finally increased root biomass. These morphological responses correlated with high and specific activation of genes encoding regulators of cell cycle and enzymes involved in cell wall biogenesis, growth and remodeling. Comparative analysis of poplar and Arabidopsis root transcriptomes under nitrogen deficiency indicated many similarities and diversification in the response in the two species. A reconstruction of genetic regulatory network (GRN) analysis revealed a sub-network centered on a PtaNAC1-like transcription factor. Consistent with the GRN predictions, root-specific upregulation of PtaNAC1 in transgenic poplar plants increased root biomass and led to significant changes in the expression of the connected genes specifically under low nitrogen. PtaNAC1 and its regulatory miR164 showed inverse expression profiles during response to LN, suggesting of a micro RNA mediated attenuation of PtaNAC1 transcript abundance in response to nitrogen deprivation. Poplar roots from low nitrogen treated and untreated from in vitro condition was selected for RNA extraction and hybridization on Affymetrix microarrays. Roots were sampled at 6, 12, 24, 48, 96 and 504h after transfer to control and low nitrogen media and RNA was extacted.

ORGANISM(S): Populus tremula x Populus alba

SUBMITTER: Victor Busov

PROVIDER: E-GEOD-43162 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Nitrogen deprivation promotes Populus root growth through global transcriptome reprogramming and activation of hierarchical genetic networks.

Wei Hairong H Yordanov Yordan S YS Georgieva Tatyana T Li Xiang X Busov Victor V

The New phytologist 20130625 2

We show a distinct and previously poorly characterized response of poplar (Populus tremula × Populus alba) roots to low nitrogen (LN), which involves activation of root growth and significant transcriptome reprogramming. Analysis of the temporal patterns of enriched ontologies among the differentially expressed genes revealed an ordered assembly of functionally cohesive biological events that aligned well with growth and morphological responses. A core set of 28 biological processes was signific ...[more]

PMID: 23795675

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Project description:The organs of multicellular species are comprised of cell types that must function together to perform specific tasks. One critical organ function is responding to internal or external change but little is known about how responses are tailored to specific cell types or coordinated among them on a global level. Here we use cellular profiling of five Arabidopsis root cell types in response to a limiting resource, nitrogen, to uncover a vast and predominantly cell-specific response that was largely undetectable using traditional methods. These methods reveal a new class of cell-specific nitrogen responses. As a proof-of-principle, we dissected one cell-specific response circuit that mediates nitrogen-induced changes in root branching from pericycle cells. Thus, cellular response profiling links gene modules to discrete functions in specific cell types. Experiment Overall Design: The whole experiment was carried out in triplicate with 84 chips in total (28 experiments). The nitrogen response in 5 FACS-sorted root cell types (LRC, lateral root cap; EpiC, epidermis and cortex; EndoP, endodermis and pericycle; Peri, pericycle; Stele, stele), protoplasts and Col-0 whole roots was assayed using microarrays. 5mM KNO3 was used as a nitrogen treatment for 2 hours. 5mM KCl was used as a control treatment for the same length of time. 1mM MSX in combination with 5mM KNO3 (or with 5mM KCl as a control) was used to block the assimilation of KNO3, and 5mM Gln added to restore it in order to separate KNO3 effects from assimilated-nitrogen effects. 5mM KNO3 was either maintained in the protoplast-generating solution (continuous treat) or not (transitory treat) to test how to best preserve the cellular nitrogen-response during the 1 hr protoplast generating procedure. As controls we used protoplasts, whole roots frozen directly after the 2hr treatment or 3.5hr treatment, or whole roots incubated in protoplast-generating solution (minus enzymes; transitory or continuous treated) and then frozen. After FACS-sorting or mock FACS-sorting cells were frozen.

Project description:We investigated the morphological roots decisions of Arabidopsis in a NO3- heterogeneous medium. To do so, we used the Split-Root System which is an experimental set up to assess root decisions in nutrient heterogeneous medium. Split-root plants have been subjected to three different treatments. ‘Control KNO3’ plants received KNO3 on both sides of the root system (C.NO3) and ‘Control KCl’ plants received KCl on both sides (C.KCl) as a nitrogen deprivation treatment. 'Split' plants received KNO3 on one side (Sp.NO3) and KCl on the other side (Sp.KCl) of the root system to assess the root decision-making in a heterogeneous environment. We observed that the total lateral roots length in the Sp.NO3 and C.KCl compartments is induced as compared to C.NO3 and Sp.KCl compartments. This corresponds to a root proliferation response in strategic territories to compensate the nitrogen deprivation. To decipher the molecular basis of this morphological root response on day 4 after the beginning of the split-root treatment, we used a transcriptomic approach on roots at 2hours, 8 hours and 2 days after the beginning of the treatment. From our microarrays data, we have identified a global set of 150 genes for which the expression pattern match with the lateral roots responses. Among them, we selected 8 early marker genes of the root decisions, which allowed us to show that the shoots and the NO3- itself are essential for the decision. Finally, we tested the role of the cytokinins phytohormones as a NO3--derived systemic signal in the root decision. Interestingly, we have demonstrated that the systemic cytokinins are involved into the decision of inducing maker genes expression and making lateral roots in the Sp.NO3 compartment specifically. 36 samples were analyzed. They correspond to three biological repeats of the C.NO3, Sp.NO3, Sp.KCl and C.KCl root samples (12 samples) that we have collected at 2hours, 8 hours and 2 days (12 samples x 3 time points) after the beginning of the split-root treatment. We analyzed the normalized microarrays data by using a three way ANOVA. The three factors of the ANOVA are 1) presence/absence of NO3-, 2) split/control and 3) time. The measures of the significance of each probe were done by the Q-value method (q<0.2, panova<0.001). The genes differentially expressed between the C.NO3 and Sp.NO3 samples, and the C.KCl and Sp.KCl samples were determined by the post-hoc Tukey test (p<0.05).

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Dataset Information

Expression data from poplar roots under nitrogen limitation

Publications

Nitrogen deprivation promotes Populus root growth through global transcriptome reprogramming and activation of hierarchical genetic networks.

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