Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of Medicago truncatula root meristem cells

ABSTRACT: The root apical meristems (RAM) is established during embryogenesis and serves as a source of stem cells for plant growth and organogenesis. Young roots have a simple structure and meristeamtic and non-meristematic cells can be differentiated based on their location. We have used the Affymetrix Medicago Genome Array GeneChip to compare tissue from the root meristem and non-meristematic tissue to identify meristem specific candidate genes based on changes in gene expression before and after differentiation Experiment Overall Design: Roots were sectioned separating meristematic (root-tip) and non-meristematic root tissue; total RNA was extracted and used for hybridization to Affymetrix arrays

ORGANISM(S): Medicago truncatula

SUBMITTER: Peta Holmes

PROVIDER: E-GEOD-8115 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Transcriptional profiling of Medicago truncatula meristematic root cells.

Holmes Peta P Goffard Nicolas N Weiller Georg F GF Rolfe Barry G BG Imin Nijat N

BMC plant biology 20080227

<h4>Background</h4>The root apical meristem of crop and model legume Medicago truncatula is a significantly different stem cell system to that of the widely studied model plant species Arabidopsis thaliana. In this study we used the Affymetrix Medicago GeneChip(R) to compare the transcriptomes of meristem and non-meristematic root to identify root meristem specific candidate genes.<h4>Results</h4>Using mRNA from root meristem and non-meristem we were able to identify 324 and 363 transcripts diff ...[more]

PMID: 18302802

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Project description:Knowledge about an organismâs cell and tissue-specific transcriptional repertoire is essential for understanding the gene regulatory circuits that control key developmental events. The shoot apical meristem (SAM) is responsible for development of all the above ground parts of plants. Our understanding of SAM at the molecular level is far from complete. The present work investigates the global gene expression repertoire of SAMs in the garden pea (Pisum sativum). To this end, 10,346 EST sequences representing 7611 unique genes were generated from pea SAM cDNA libraries. These sequences, together with previously reported ESTs, were used to construct a 12K oligonucleotide array used to identify genes exhibiting differential SAM expression, as compared to the axillary meristem, root apical meristem, and non-meristematic tissues. We identified a number of genes that are predominantly expressed in specific cell layers or domains of the SAM, and thus are likely components of the gene networks involved in stem cell maintenance and initiation of lateral organ primordial cells. In situ hybridization confirmed the spatial localisation of some of these key genes within the SAM. Our data also indicate the diversification of some gene expression patterns and functions in legume crop plants. RNA samples were hybridized to two-colour Combimatrix arrays manufactured with a custom library of 11958 probes. The limma software package for R (Smyth, 2005) was used in subsequent statistical analysis of the data generated. On examination of the data during quality control assessment, it became evident that the Cy3 channel showed little dynamic range and background correction and normalisation could not correct for this. Therefore only the Cy5 channel was used in the subsequent analysis. This resulted in somewhat unbalanced sample sizes with six replicates of SAM and one each of RAM, AM and NM. Nevertheless, linear modelling and empirical Bayes moderated t-statistics (Smyth, 2004) used in the statistical analysis allows variance information to be borrowed across both samples and genes, resulting in reliable statistical inference even for the groups with only one sample.

Project description:The mechanisms ensuring balanced growth remain a critical question in developmental biology. In plants, this balance relies on spatiotemporal integration of hormonal signaling pathways, but the understanding of the precise contribution of each hormone is just beginning to take form. Brassinosteroid (BR) hormone, is shown here to have opposing effects on root meristem size, depending on its site of action. BR is demonstrated to both delay and promote onset of stem cell daughter differentiation, when acting in the outer tissue of the root meristem, the epidermis, and the inner-most tissue, the stele, respectively. To understand the molecular basis of this phenomenon, a comprehensive spatiotemporal translatome mapping of Arabidopsis roots was performed. Analyses of wild type and mutants featuring different distributions of BR, revealed autonomous, tissue-specific gene responses to BR, implying its contrasting tissue-dependent impact on growth. BR-induced genes were primarily detected in epidermal cells of the basal meristem zone and were enriched by auxin-related genes. In contrast, repressed BR genes prevailed in the stele of the apical meristem zone. Furthermore, auxin was found to mediate the growth-promoting impact of BR signaling originating in the epidermis, while BR signaling in the stele buffered this effect. We propose that context-specific BR activity and responses are oppositely interpreted at the organ level, ensuring coherent growth. 24 samples of polyribosome-associated mRNA (following 0, 3, and 8 hours of BR treatment, in two biological repetitions), were collected. RNA samples were sequenced on an Illumina HiSeq 2500, to obtain 50 bp single-end reads. These reads were aligned to the TAIR10 assembly of the Arabidopsis thaliana genome, using Tophat2 v2.0.9. Transcript coordinates from the TAIR10 reference set were used to guide the alignment process. After alignment, the numbers of reads per transcript were estimated using HTSeq v0.5.3p3, and DESeq2 v1.2.8 was used to normalize read counts and call differentially expressed genes.

Dataset Information

Transcription profiling of Medicago truncatula root meristem cells

Publications

Transcriptional profiling of Medicago truncatula meristematic root cells.

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