| Carol A. Ishimaru
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.
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