- Phytobacteriology and molecular plant-microbe interactions
- Molecular basis of pathogenicity of bacterial plant pathogens, including mechanisms of water-soaking (Wts) and wilting and regulation of pathogenicity genes
Extracellular polysaccharides as pathogencity factors using the corn pathogen, Pantoea stewartii as a model system; Hrp type-III protein secretion system, Wts effector proteins and cell death and/or suppression of host defenses; nature of the secreted Wts proteins and the regulation of the hrp/wts genes
Dr. Dave Coplin's interests involve the molecular biology of plant-bacteria interactions. He is currently studying the genetics of the corn pathogen, Erwinia stewartii. The major pathogenicity factor of this bacterium is an extracellular polysaccharide (EPS) that causes vascular blockage and wilting. Dr. Coplin's laboratory group is currently characterizing and sequencing the genes involved in production of the EPS and their regulation. As an early step in pathogenesis, E. stewartii damages host cell membranes by an unknown mechanism, which involves EPS and a hypothetical cell-leakage factor. Dr. Coplin's group has isolated many nonpathogenic mutants blocked in lesion formation and has cloned the corresponding pathogenicity genes. These genes have turned out to be homologous to a group of conserved pathogenicity genes found in many other plant pathogenic bacteria, which are called hrp genes because they are required for both a hypersensitive response on a resistant host and pathogenicity on a susceptible host. To date their function is unknown, but the study of hrp genes in E. stewartii is interesting because it is the only bacterium known to possess them that does not cause hypersensitivity on any plant. The characterization of the very large hrp gene cluster in E. stewartii is a second major project in Dr. Coplin's laboratory.
Schollmeyer M, Langlotz C, Huber A, Coplin DL, Geider K. 2012, Variations in the molecular masses of the capsular exopolysaccharides amylovoran, pyrifolan and stewartan. INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 50(3): 518-522.
Jong Hyun Ham, Doris R. Majerczak, Kinya Nomura, Christy Mecey, Francisco Uribe, Sheng-Hang Ye, David Mackey, and David L. Coplin. 2009. Multiple Activities of the Plant Pathogen Type III Effector Proteins WtsE and AvrE Require WxxxE Motifs. Molecular Plant Microbe Interactions Vol. 22(6): 703-712. One of the most popular downloaded articles from this issue.
Coplin, D.L., Ham, J.H., Majerczak,D.R., and Mackey, D.M. 2008. The WtsE virulence effector from Pantoea stewartii, a plant signal mimic? Acta Hort. 793:203-212.
Ham, J.H., Majerczak, D.R., Ewert, S., Mysore-Venkatara, S., Mackey, D., and Coplin, D.L. 2008. WtsE, an AvrE-family type III effector protein of Pantoea stewartii subsp. stewartii, causes cell death in nonhost plants. Mol. Plant Pathol. 9:633-643.