TheCan Caesar-TonThat

Research Microbiologist
Phone: 406.433.9415
Fax: 406.433.5038
E-mail: caesart@sidney.ars.usda.gov

 

 

Additional Pages: Research Projects,* Publications*

*Taken from the Agricultural Research Information System (ARIS) database.

 

 

EDUCATION

 
M.S. Microbiology 1974 University of Geneva, Switzerland
Ph. D. Microbiology 1979 University of Geneva, Switzerland

 


CURRENT RESEARCH

 

NATIONAL PROGRAM 202: SOIL RESOURCE MANAGEMENT

Dryland soils of the Northern Plains have lost, on average 50% of their original organic matter due to excessive tillage and summer fallow. The decline in organic matter is accompanied by structural deterioration of soils (decrease of soil aggregation), reduced water infiltration, poor oxygenation, and increased erosion. To evaluate sustainability of agricultural management practices, the assessment of soil health using various indicators of soil is needed. The goals of Dr. Caesar are to evaluate the interactions between soil management and soil biota, in particular the effects of soil disturbance (till versus no till management practices) and crop residues on specific saprophytic basidiomycete fungi that can aggregate soil, forming water stable aggregates. She develops knowledge and techniques for sustainable soil and crop management that emphasizes preservation and enhancement of these specific fungi for the benefit of soil structure. The work identifies the need to inquiring not only about relation to the mechanisms by which these fungi stabilize soil but also to the wider problems of understanding the importance of this class of fungi and their role in different litter resource ecosystems.

 

NATIONAL PROGRAM 207: INTEGRATED FARMING SYSTEMS

Control of leaf spot disease of sugar beets (b vulgaris L.) caused by Cercospora beticola has relied mostly on chemical control.  Severe disease incidences result in significant yield losses and reduced sugar content of beets as well as expensive applications of pesticides.


C. beticola Sacc. has been shown to produce cercosporin, a deep red colored, light activated polyketide toxin on a wide range of organisms such as other fungi, bacteria, plants and animals.  Cercosporin has since been isolated from a large number of Cercospora species and from Cercospora infected-plants.  In a biological approach, Dr. Caesar, in collaboration with Dr. R. T. Lartey (ARS, Sidney, MT), investigates the mechanisms of degradation and detoxification of cercosporin by laccase, a ligninolytic enzyme sectreted by antagonistic basidiomycete fungi.  Degradation of the toxin by laccase will prevent break down of plant cell membranes by cercosporin resulting in starvation of Cercospora.

 

 

RESEARCH EXPERIENCE

 

After completing her Doctorate of Science (Ph.D.) in 1979 at the University of Geneva, Switzerland, she was hired as a research microbiologist at the Department of Microbiology in Geneva, Switzerland to conduct research on cellular mechanisms of the fungus Neurospora crassa in response to heat shock. She demonstrated at the ultrastructural level that the gene translation process is curtailed in heat-treated fungal cells. In 1983, she was awarded a competitive grant from the Swiss Foundation of Science to spend two years at the Department of Plant Pathology at Cornell University working in the laboratory of Dr. H.C. Hoch studying clathrin coated vesicles from filamentous fungi (Neurospora crassa and Uromyces phaseoli). She also used Neurospora crassa to study the mechanisms by which the fungicide benomyl alters membrane b-tubulin affecting linear growth. In 1986, she moved to the Department of Plant Pathology, at the University of California-Berkeley, for a research scientist position working on mechanisms of adhesion for fungi. Then she moved to Bozeman, Montana, where she accepted an assistant research professor position at Montana State University in the Department of Microbiology in collaboration with Dr. Joan M. Henson. They investigated the role of fungal melanin in bioremediation. This research provided direct evidence that copper stimulates melanin production and that melanin plays an important role in copper sequestration by forming insoluble metal sulfides that can be trapped in cell walls. This data helped to explain why copper-based fungicides failed to control diseases caused by Gaeumannomyces graminis var. graminis and thus provides important knowledge for the development of effective control strategies for this pathogen. She also studied in collaboration with Dr. Jim E. Cutler on the effects of monoclonal antibody (Mab B6.1) to the human pathogen Candida albicans on protection of candidiasis in comparison with the effects of the non-protective Mab B6 for ability to support neutrophil (polymorphonuclear leukocyte [PMN]) candidacidal activity.
 

 

RELATED WEBPAGES

 

Agricultural Systems Research Unit Projects

Enzyme May Protect Sugar Beets From Leaf Spot Disease (.PDF)

 

 

SELECTED PUBLICATIONS: