Nematode Infection Triggers the de Novo Formation of Unloading Phloem That Allows Macromolecular Trafficking of Green Fluorescent Protein into Syncytia
Open Access
- 1 May 2005
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 138 (1), 383-392
- https://doi.org/10.1104/pp.104.058800
Abstract
Syncytial feeding complexes induced by the cyst nematode Heterodera schachtii represent strong metabolic sinks for photoassimilates. These newly formed structures were described to be symplastically isolated from the surrounding root tissue and their mechanism of carbohydrate import has repeatedly been under investigation. Here, we present analyses of the symplastic connectivity between the root phloem and these syncytia in nematode-infected Arabidopsis (Arabidopsis thaliana) plants expressing the gene of the green fluorescent protein (GFP) or of different GFP fusions under the control of the companion cell (CC)-specific AtSUC2 promoter. In the same plants, phloem differentiation during syncytium formation was monitored using cell-specific antibodies for CCs or sieve elements (SEs). Our results demonstrate that free, CC-derived GFP moved freely from the phloem into the syncytial domain. No or only marginal cell-to-cell passage of GFP was observed into other root cells adjacent to these syncytia. In contrast, membrane-anchored GFP variants as well as soluble GFP fusions with increased molecular masses were restricted to the SE-CC complex. The presented data also show that nematode infection triggers the de novo formation of phloem containing an approximately 3-fold excess of SEs over CCs. This newly formed phloem exhibits typical properties of unloading phloem previously described in other sink tissues. Our results reveal the existence of a symplastic pathway between phloem CCs and nematode-induced syncytia. The plasmodesmata responsible for this symplastic connectivity allow the cell-to-cell movement of macromolecules up to 30 kD and are likely to represent the major or exclusive path for the supply of assimilates from the phloem into the syncytial complex.Keywords
This publication has 42 references indexed in Scilit:
- Functional Characterization and Expression Analyses of the Glucose-Specific AtSTP9 Monosaccharide Transporter in Pollen of ArabidopsisPlant Physiology, 2003
- The Companion Cell-Specific Arabidopsis Disaccharide Carrier AtSUC2 Is Expressed in Nematode-Induced SyncytiaPlant Physiology, 2003
- Changes in mRNA Abundance within Heterodera schachtii-Infected Roots of Arabidopsis thalianaMolecular Plant-Microbe Interactions®, 2000
- Isolation of theLEMMI9Gene and Promoter Analysis During a Compatible Plant-Nematode InteractionMolecular Plant-Microbe Interactions®, 1999
- Symplastic continuity in Agrobacterium tumefaciens-induced tumoursJournal of Experimental Botany, 1999
- Regulatory sequences of Arabidopsis drive reporter gene expression in nematode feeding structures.Plant Cell, 1997
- Induction of Phloem Unloading in Arabidopsis thaliana Roots by the Parasitic Nematode Heterodera schachtiiPlant Physiology, 1996
- Changes in the structure ofArabidopsis thaliana during female development of the plant-parasitic nematodeHeterodera schachtiiProtoplasma, 1996
- Differential gene expression in nematode‐induced feeding structures of transgenic plants harbouring promoter—gusA fusion constructsThe Plant Journal, 1993
- A Revised Medium for Rapid Growth and Bio Assays with Tobacco Tissue CulturesPhysiologia Plantarum, 1962