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A synthetic peptide shows retro- and anterograde neuronal transport before disrupting the chemosensation of plant-pathogenic nematodes.

Wang D, Jones LM, Urwin PE, Atkinson HJ - PLoS ONE (2011)

Bottom Line: The peptide takes 2.5 h to reach the neuronal cell bodies.The peptide probably undergoes transport along the dye-filling non-cholinergic chemoreceptive neurons to their synapses where it is taken up by the interneurons to which they connect.Coordinated responses to chemoreception are disrupted when the sub-set of cholinergic interneurons secrete the peptide at synapses that have post-synaptic nicotinic acetylcholine receptors.

View Article: PubMed Central - PubMed

Affiliation: Centre for Plant Science, University of Leeds, Leeds, United Kingdom.

ABSTRACT
Cyst nematodes are a group of plant pathogens each with a defined host range that cause major losses to crops including potato, soybean and sugar beet. The infective mobile stage hatches from dormant eggs and moves a short distance through the soil to plant roots, which it then invades. A novel strategy for control has recently been proposed in which the plant is able to secrete a peptide which disorientates the infective stage and prevents invasion of the pathogen. This study provides indirect evidence to support the mechanism by which one such peptide disrupts chemosensory function in nematodes. The peptide is a disulphide-constrained 7-mer with the amino acid sequence CTTMHPRLC that binds to nicotinic acetylcholine receptors. A fluorescently tagged version of this peptide with both epifluorescent and confocal microscopy was used to demonstrate that retrograde transport occurs from an aqueous environment along bare-ending primary cilia of chemoreceptive sensilla. The peptide is transported to the cell bodies of these neurons and on to a limited number of other neurons to which they connect. It appears to be localised in both neuronal processes and organelles adjacent to nuclei of some neurons suggesting it could be transported through the Golgi apparatus. The peptide takes 2.5 h to reach the neuronal cell bodies. Comparative studies established that similar but less abundant uptake occurs for Caenorhabditis elegans along its well studied dye-filling chemoreceptive neurons. Incubation in peptide solution or root-exudate from transgenic plants that secrete the peptide disrupted normal orientation of infective cyst nematodes to host root diffusate. The peptide probably undergoes transport along the dye-filling non-cholinergic chemoreceptive neurons to their synapses where it is taken up by the interneurons to which they connect. Coordinated responses to chemoreception are disrupted when the sub-set of cholinergic interneurons secrete the peptide at synapses that have post-synaptic nicotinic acetylcholine receptors.

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Neuronal uptake of Alexa Fluor 488-labelled nAChRbp by J2s of Globodera pallida.J2 of G. pallida were incubated in 281 µM nAChRbp labelled with Alexa Fluor 488 for varying periods of 1–16 h and the labelled peptide was then visualised by epifluorescence. Images with one amphidial pouch visualised are lateral views and those with two amphidial pouches visualised are dorsal or ventral views. The scale bar of 10 µm applies to all images.
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pone-0017475-g006: Neuronal uptake of Alexa Fluor 488-labelled nAChRbp by J2s of Globodera pallida.J2 of G. pallida were incubated in 281 µM nAChRbp labelled with Alexa Fluor 488 for varying periods of 1–16 h and the labelled peptide was then visualised by epifluorescence. Images with one amphidial pouch visualised are lateral views and those with two amphidial pouches visualised are dorsal or ventral views. The scale bar of 10 µm applies to all images.

Mentions: The J2 of the potato cyst nematode, G. pallida, also demonstrated uptake of the labelled peptide along their amphidial neurons and showed a very similar pattern of fluorescence to that of J2 H. schachtii after 16 h incubation in 281 µM labelled nAChRbp (Fig. 6). For this nematode a time course of incubation in 281 µM labelled peptide was carried out to explore the rate of peptide transport. The labelled peptide provided a high level of fluorescence in the region of the amphidial pouches by 2 h with some fluorescence apparent in the region of the cell bodies of the amphidial neurons by 4.5 h. Emissions along the dendrite were very evident at 12 h and 16 h with some fluorescence detectable from the nerve ring at 9 h and certainly by 16 h. Two main points are apparent. After 2 h the region of the amphidial pouches had become fluorescent but the labelled peptide took about another 2 h to travel the 55–70 µm along dendrites to the region of the amphidial cell bodies. Additionally, the labelled peptide accumulated in this region with more than 4.5 h exposure to 281 µM peptide. When only 4 µM labelled peptide was used, fluorescence was not evident in the amphidial pouches, their dendrites or cell bodies at but it was visualised at both 10 µM and 40 µM with considerable uptake evident for nematodes soaked in 281 µM peptide (Fig. 7).


A synthetic peptide shows retro- and anterograde neuronal transport before disrupting the chemosensation of plant-pathogenic nematodes.

Wang D, Jones LM, Urwin PE, Atkinson HJ - PLoS ONE (2011)

Neuronal uptake of Alexa Fluor 488-labelled nAChRbp by J2s of Globodera pallida.J2 of G. pallida were incubated in 281 µM nAChRbp labelled with Alexa Fluor 488 for varying periods of 1–16 h and the labelled peptide was then visualised by epifluorescence. Images with one amphidial pouch visualised are lateral views and those with two amphidial pouches visualised are dorsal or ventral views. The scale bar of 10 µm applies to all images.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3049761&req=5

pone-0017475-g006: Neuronal uptake of Alexa Fluor 488-labelled nAChRbp by J2s of Globodera pallida.J2 of G. pallida were incubated in 281 µM nAChRbp labelled with Alexa Fluor 488 for varying periods of 1–16 h and the labelled peptide was then visualised by epifluorescence. Images with one amphidial pouch visualised are lateral views and those with two amphidial pouches visualised are dorsal or ventral views. The scale bar of 10 µm applies to all images.
Mentions: The J2 of the potato cyst nematode, G. pallida, also demonstrated uptake of the labelled peptide along their amphidial neurons and showed a very similar pattern of fluorescence to that of J2 H. schachtii after 16 h incubation in 281 µM labelled nAChRbp (Fig. 6). For this nematode a time course of incubation in 281 µM labelled peptide was carried out to explore the rate of peptide transport. The labelled peptide provided a high level of fluorescence in the region of the amphidial pouches by 2 h with some fluorescence apparent in the region of the cell bodies of the amphidial neurons by 4.5 h. Emissions along the dendrite were very evident at 12 h and 16 h with some fluorescence detectable from the nerve ring at 9 h and certainly by 16 h. Two main points are apparent. After 2 h the region of the amphidial pouches had become fluorescent but the labelled peptide took about another 2 h to travel the 55–70 µm along dendrites to the region of the amphidial cell bodies. Additionally, the labelled peptide accumulated in this region with more than 4.5 h exposure to 281 µM peptide. When only 4 µM labelled peptide was used, fluorescence was not evident in the amphidial pouches, their dendrites or cell bodies at but it was visualised at both 10 µM and 40 µM with considerable uptake evident for nematodes soaked in 281 µM peptide (Fig. 7).

Bottom Line: The peptide takes 2.5 h to reach the neuronal cell bodies.The peptide probably undergoes transport along the dye-filling non-cholinergic chemoreceptive neurons to their synapses where it is taken up by the interneurons to which they connect.Coordinated responses to chemoreception are disrupted when the sub-set of cholinergic interneurons secrete the peptide at synapses that have post-synaptic nicotinic acetylcholine receptors.

View Article: PubMed Central - PubMed

Affiliation: Centre for Plant Science, University of Leeds, Leeds, United Kingdom.

ABSTRACT
Cyst nematodes are a group of plant pathogens each with a defined host range that cause major losses to crops including potato, soybean and sugar beet. The infective mobile stage hatches from dormant eggs and moves a short distance through the soil to plant roots, which it then invades. A novel strategy for control has recently been proposed in which the plant is able to secrete a peptide which disorientates the infective stage and prevents invasion of the pathogen. This study provides indirect evidence to support the mechanism by which one such peptide disrupts chemosensory function in nematodes. The peptide is a disulphide-constrained 7-mer with the amino acid sequence CTTMHPRLC that binds to nicotinic acetylcholine receptors. A fluorescently tagged version of this peptide with both epifluorescent and confocal microscopy was used to demonstrate that retrograde transport occurs from an aqueous environment along bare-ending primary cilia of chemoreceptive sensilla. The peptide is transported to the cell bodies of these neurons and on to a limited number of other neurons to which they connect. It appears to be localised in both neuronal processes and organelles adjacent to nuclei of some neurons suggesting it could be transported through the Golgi apparatus. The peptide takes 2.5 h to reach the neuronal cell bodies. Comparative studies established that similar but less abundant uptake occurs for Caenorhabditis elegans along its well studied dye-filling chemoreceptive neurons. Incubation in peptide solution or root-exudate from transgenic plants that secrete the peptide disrupted normal orientation of infective cyst nematodes to host root diffusate. The peptide probably undergoes transport along the dye-filling non-cholinergic chemoreceptive neurons to their synapses where it is taken up by the interneurons to which they connect. Coordinated responses to chemoreception are disrupted when the sub-set of cholinergic interneurons secrete the peptide at synapses that have post-synaptic nicotinic acetylcholine receptors.

Show MeSH
Related in: MedlinePlus