A phloem-enriched cDNA library from Ricinus: insights into phloem function
Open Access
- 25 August 2006
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Experimental Botany
- Vol. 57 (12), 3183-3193
- https://doi.org/10.1093/jxb/erl082
Abstract
The aim of this study was to identify genes that are expressed in the phloem. Increased knowledge of phloem regulation will contribute to our understanding of its many roles, from transport of solutes to information about interactions with pathogens. A cDNA library constructed from phloem-enriched sap exuding from cut Ricinus communis (L.) hypocotyls was sequenced. To assess contamination from other tissues, two libraries were constructed: one using the first 15 min of exudation and the other from sap collected after 120 min of exudation had elapsed. Of 1012 clones sequenced, 158 unique transcripts were identified. The presence of marker molecules such as profilin, the low occurrence of chloroplast-related mRNAs, and the sieve element localization of constituent mRNA using in situ hybridization were consistent with a phloem origin of the sap. Functional analysis of the cDNAs revealed classifications including ribosomal function, interaction with the environment, transport, DNA/RNA binding, and protein turnover. An analysis of the closest Arabidopsis thaliana (L.) homologue for each clone indicated that genes involved in cell localization, protein synthesis, tissue localization, organ localization, organ differentiation, and cell fate were represented at twice the level occurring in the whole Arabidopsis genome. The transcripts found in this phloem-enriched library are discussed in the context of phloem function and the relationship between the companion cell and sieve element.Keywords
This publication has 48 references indexed in Scilit:
- The mRNA of the Arabidopsis Gene FT Moves from Leaf to Shoot Apex and Induces FloweringScience, 2005
- Pathogen‐induced resistance and alarm signals in the phloemMolecular Plant Pathology, 2004
- Arabidopsis RADICAL-INDUCED CELL DEATH1 Belongs to the WWE Protein–Protein Interaction Domain Protein Family and Modulates Abscisic Acid, Ethylene, and Methyl Jasmonate ResponsesPlant Cell, 2004
- Evidence That Sucrose Loaded into the Phloem of a Poplar Leaf Is Used Directly by Sucrose Synthase Associated with Various β-Glucan Synthases in the StemPlant Physiology, 2004
- TheBrassica napus extAextensin gene negative regulatory region controls expression in response to mechanical stressesPlant, Cell & Environment, 2003
- Construction of a specialized cDNA library from plant cells isolated by laser capture microdissection: toward comprehensive analysis of the genes expressed in the rice phloemThe Plant Journal, 2002
- Use of aphid stylectomy and RT‐PCR for the detection of transporter mRNAs in sieve elementsJournal of Experimental Botany, 2002
- Sugar transporters in higher plants – a diversity of roles and complex regulationTrends in Plant Science, 2000
- Aphid stylectomy reveals an osmotic step between sieve tube and cortical cells in barley rootsJournal of Experimental Botany, 1996
- Monoclonal Antibodies Against Phloem P-Protein from Plant Tissue Cultures. I. Microscopy and Biochemical AnalysisAmerican Journal of Botany, 1994