Leland S. Pierson III
is an Associate Professor in the Department of Plant Pathology at the University of Arizona. He received his Bachelors degree in Microbiology from the University of California, Davis and his and Ph.D. degree in Microbiology from Washington State University. He was a postdoctoral research associate in the laboratory of Dr. Linda S. Thomashow at the USDA-ARS Root Disease and Biological Control Research Unit in Pullman, Washington. There he worked on identifying mechanisms responsible for take-all disease suppression by fluorescent pseudomonads. Since his arrival at the University of Arizona, Dr. Pierson’s research has focused on the molecular genetics regulating phenazine antibiotic production in Pseudomonas aureofaciens
as a model system for how plant-associated bacteria sense their environment and regulate competitive behaviors. His laboratory demonstrated that phenazine biosynthetic gene expression is regulated at multiple levels, including population, environmental and metabolic signals. He showed that phenazines are regulated by diffusible N-acyl-homoserine lactone signals. These signals serve as a sensory transduction pathway that allows intra-population and inter-population signaling to occur on the plant root. Current research includes the influence of both positive and negative cross-communication on competition and community structure in the rhizosphere and the identification of natural anticancer compounds produced by desert rhizosphere microorganisms. He is the current chair of the APS Bacteriology Committee and chair of The University of Arizona Institutional Biosafety Committee.
Carol A. Ishimaru
is an Associate Professor in the Department of Biological Sciences and Pest Management at Colorado State University. She received her BS degree in Botany and the Ph.D. in Plant Pathology from Michigan State University. After graduating, she was a postdoctoral research associate in the laboratory of Dr. Anne K. Vidaver, University of Lincoln, Nebraska, where her interest in Gram-positive plant pathogenic coryneform bacteria began. Prior to accepting her position at CSU, Dr. Ishimaru was a postdoctoral research associate in Dr. Joyce Loper's laboratory at the USDA Horticultural Crops Research Laboratory in Corvallis, Oregon, where she identified siderophores produced by Erwinia carotovora
. Since her arrival at CSU, Dr. Ishimaru's research has focused on the molecular biology of an important coryneform pathogen of potato, Clavibacter michiganensis
. Her current efforts aim at identifying pathogenicity and virulence factors in phytopathogenic coryneforms through the application of genomic technologies developed for other plant and animal pathogens. She has served as chair of the APS Bacteriology Standing Committee. She currently chairs the ad hoc APS Bacteriology Committee, which developed a list of plant pathogenic bacteria prevalent in the United States in partial completion of a work agreement between APS and USDA/APHIS.RETURN TO APSnet FEATURE STORY