Plant –Bacterial Pathogen Interactions
My current research is directed to determining the genome sequence of the bacterial ring rot pathogen, Clavibacter michiganensis subsp. sepedonicus (Cms) and applying that information in the seed industry. Cms can survive in plants for several generations without producing noticeable disease symptoms, posing a major challenge to potato seed certification and ring rot eradication. Though high-GC (Guanine-Cytosine) gram-positive bacteria such as Cms cause significant losses in several important U.S. crops, very little is known about their molecular determinants of pathogenicity. Therefore, my long-term research goal is to identify the basis for pathogenicity in Cms. Identifying the genes affecting pathogenicity could lead to a better understanding of how this pathogen persists in apparently healthy plants. It could also provide a rationale for practical methods of reducing or eliminating latent infections.
My other research objective is to reveal any concordances in pathogenicity among high-GC gram-positive plant and animal pathogens. Very little is known about the functions or genetic regulation of a large number of predicted proteins in the genomes of actinomycetes. Almost nothing is known about how phytopathogenic coryneform bacteria respond to a host’s environment or which particular bacterial proteins are required for disease development. It is also not known if any genes required for pathogenicity in plants share homology to similar functional genes in animals, as has been shown for several gram-negative animal and plant pathogens.
Selected Publications:
Gent, D.H., Schwartz, H.F., Ishimaru, C.A., Louws, F.J., Cramer, R.A., and C. B. Lawrence. (2004). Polyphasic characterization of Xanthomonas strains from onion. Phytopathology 94:184-195
Laurila. J., M. C. Metzler, C. A. Ishimaru, and V.-M. Rokka. (2003). Infection of plant material derived from Solanum acaule with Clavibacter michiganensis ssp. sepedonicus: temperature as a determining factor in immunity of S. acaule to bacterial ring rot. Plant Pathology 52:496-504
Brown, S. E., D. L. Knudson, and C. A. Ishimaru. (2002). Linear plasmid in the genome of Clavibacter michiganensis subspecies sepedonicus. Journal of Bacteriology. 184:2841-2844.
Brown, S. E., A. A. Reilley, D. L. Knudson, and C. A. Ishimaru. (2002). Genomic fingerprinting of virulent and avirulent strains of Clavibacter michiganensis subspecies sepedonicus Current Microbiology.44:112-119.
Zinniel, D. K., P. Lambrecht, N. B. Harris, Z. Feng, D. Kuczmarski, P. Higley, C. A. Ishimaru, A. Arunakumari, R. G. Barletta, and A. K. Vidaver. 2002. Isolation and characterization of endophytic colonizing bacteria from agronomic crops and prairie plants. Applied and Environmental Microbiology. 68:2198-2208.
