Transcriptome analysis of the Arabidopsis phloem

This sudy focuses on the identification of transcripts in the shoot phloem of the model plant Arabidopsis thaliana. Transcripts expressed in the phloem tissue (parenchyma cell, companion cell, sieve element) were excised by laser microdissection pressure catapulting (LMPC). These were compared with transcripts isolated from leaf phloem exudates by EDTA-chelation technique. Optimization of sample harvest resulted in RNA of high quality from both sources. Modifications of the RNA amplification procedure obtained RNA of sufficient yield and quality for microarray experiments. Microarrays (Affymetrix, ATH1) hybridized with RNA derived from phloem tissue by LMPC or phloem sap allowed us to differentiate between phloem located and mobile transcript species. The datasets provide a search criterion for phloem-based signals and will facilitate reverse genetic studies and forward genetic screens for phloem and long distance RNA signaling mutants.

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Deeken R, Ache P, Kajahn I, Klinkenberg J, Bringmann G, Hedrich R