Manipulation of Host Signaling by Pathogens
Davis, Eric .
Nematode Secretions Signal Big Changes in Host Plant Cells.
Cyst and root-knot nematodes are microscopic worms that penetrate plant roots as motile juveniles and induce dramatic changes in gene expression of selected vascular cells to form enlarged, multinucleate, and metabolically active permanent feeding cells for the subsequent sedentary parasitic nematode life stages. The hollow mouth spear of the nematode is a stylet that is used for plant cell feeding and for secretion of the proteins produced in elaborate esophageal gland secretory cells that have evolved in phytonematodes to modify plants for parasitism. Over fifty unique parasitism genes that encode the secreted proteins of both root-knot and cyst nematodes are developmentally expressed exclusively within the esophageal gland cells throughout the course of parasitism. Both groups of nematodes share a battery of secreted cell wall hydrolytic enzymes that are expressed during nematode juvenile migration in roots, however, the nematode parasitism genes active during feeding site initiation and maintenance encode distinct secreted proteins that are more regulatory in nature. Examples include a nematode peptide domain with sequence and function similar to plant CLAVATA3 signaling peptides, secreted chorismate mutase, annexin-like proteins, a 13-amino acid peptide that can accelerate root growth and interact with plant SCARECROW-like proteins, and secreted nematode proteins with functional host nuclear localization signals. Expression of candidate nematode parasitism proteins in transformed wild-type Arabidopsis and selected mutants provides one measure of function. Expression of double-stranded RNA in plants for RNA interference of targeted nematode parasitism genes is providing both an assay of gene function and a potential means of plant resistance to nematodes.
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1 - North Carolina State University, Plant Pathology, 840 Method Rd., Unit 4, Box 7903
Dept. Plant Pathology, Dept. Plant Pathology, Raleigh, NC, 27607, United States
Presentation Type: ASPB Major Symposium
Location: International Ballroom/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:30 AM