Additional Pages:Research Projects,* Publications*
*Taken from the Agricultural Research Information System (ARIS) database.
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.
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.
ARS: NEWS & EVENTS (This link leads to Dr. Caesar's query within ARS's news and events)
Sainju, U.M., Lenssen, A.W., Caesar, T., Jabro, J.D., Lartey, R.T., Evans, R.G., Allen, B.L. 2011. Dryland residue and soil orgranic matter as influenced by tillage, crop rotation, and cultural practice. Plant and Soil Journal. 338:27-41. (PDF, 213 KB)
Caesar, T., Sainju, U.M., Wright, S.E., Shelver, W.L., Kolberg, R.L., West, M.S. 2010. Long-term tillage and cropping effects on biological properties associated with soil aggregation in semi-arid eastern Montana, USA. Biology and Fertility of Soils. 47:157-165. (PDF; 166KB)
Caesar, A.J., Caesar, T., Lartey, R.T. 2010. First report of anthracnose stem Canker of the invasive perennial weed Lepidium draba caused by Colletotrichum higginsianum in Europe. Plant Disease. 94:1166-1166.
Caesar, A.J., Caesar, T., Maathuis, M. 2010. Pathogenicity, characterization and comparative virulence of Rhizoctonia spp. from insect-galled roots of Lepidium draba in Europe. Biological Control. 52(2): 140-148.
Caesar, A.J., Caesar, T., Sainju, U.M. 2010. The plant pathology of native plant restoration. Environmental Research. Volume 4 Issue 3/4.
Caesar, T., Lenssen, A.W., Caesar, A.J., Sainju, U.M., Gaskin, J.F. 2010. Effects of tillage on microbial populations associated to soil aggregates under dryland spring wheat system. European Journal of Soil Biology. 46:119-127. (PDF; 409 KB)
Lartey, R.T., Caesar, T., Lenssen, A.W., Eckhoff, J., Hanson, S.L., Evans, R.G. 2010. Direct Polymerase Chain Reaction-Based Detection of Cercospora Beticola in Field Soils. Plant Disease. 94(9):1100-1104. (PDF; 198 KB)
Sainju, U.M., Jabro, J.D., Caesar, T. 2010. Tillage, Cropping Sequence, and Nitrogen Fertilization Effects on Dryland Soil Carbon Dioxide Emission and Carbon Content. Journal of Environmental Quality. 39:935-945. (PDF; 1508 KB)
Sainju, U.M., Stevens, W.B., Caesar, T., Jabro, J.D. 2010. Land Use and Management Practices Impact on Plant Biomass Carbon and Soil Carbon Dioxide Emission. Soil Science Society of America Journal. 74:1613-1622. (PDF; 782 KB)
Caesar, A.J., Lartey, R.T., Caesar, T. 2009. First Report of a Root and Crown Disease caused by Rhizoctonia solani on Centaurea maculosa in Russia. Plant Disease. 93(12): 1350-1350. (PDF; 628 KB)
Caesar, T., Lartey, R.T., Solberg Rodier, L.L., Caesar, A.J. 2009. Effects of Basidiomycete laccase on Cercosporin. Journal of Plant Pathology. 91(2):347-355. (PDF; 341 KB)
Lartey, R.T., Lenssen, A.W., Caesar, T., Eckhoff, J., Hanson, S.L., and Evans, R.G. 2009. Preliminary evaluation of Laetisaria arvalis as chemical seed treatment alternative in sugarbeet. 35th General Meeting of American Society of Sugar Beet Technologists. 1(35):48. (PDF; 198 KB)
Pikul, Jr., J.L., Chilom, G., Rice, J., Eynard, A., Schumacher, T.E., Nichols, K., Johnson, J.M.F., Wright, S., Caesar, T., Ellsbury, M. 2009. Organic Matter and Water Stability of Field Aggregates Affected by Tillage in South Dakota. Soil Science Society of America Journal. 73:197-206. (PDF; 799 KB)
Sainju, U.M., Caesar, T., Jabro, J.D. 2009. Carbon and Nitrogen Fractions in Dryland Soil Aggregates Affected by Long-term Tillage and Cropping Sequence. Soil Science Society of America Journal. 73(5): 1488-1495. (PDF; 1536 KB)
Sainju, U.M., Caesar, T., Lenssen, A.W., Evans, R.G., Kolberg, R.L. 2009. Tillage and cropping sequence impacts on nitrogen cycling in dryland farming in eastern Montana, USA. Soil & Tillage Research. 103:332-341. (PDF; 365 KB)
Sainju, U.M., Lenssen, A.W., Caesar, T., Evans, R.G. 2009. Dryland Crop Yields and Soil Organic Matter as Influenced by Long-Term Tillage and Cropping Sequence. Agronomy Journal. 101:243-251. (PDF; 1111 KB)
Smith, D.J., Oliver, C.E., Shelver, W.L., Caesar, T., Anderson, R.C. 2009. Clorate Metabolism in Pure Cultures of Escherichia Coli 0157:H7 Pretreated with Either Nitrate or Chlorate. Journal of Agricultural and Food Chemistry. 57:10216-10224. (PDF; 896 KB)
Caesar, T., Busscher, W.J., Novak, J.M., Gaskin, J.F., Kim, Y. 2008. Effects of Polyacrylamide and Organic Matter on Microbes associated to Soil Aggregation of Norfolk Loamy Sand. Applied Soil Ecology. 40:240-249. (PDF; 1238 KB)
Busscher, W.J., Novak, J.M., Caesar, T., Sojka, R.E. 2007. Amendments to increase aggregation in United States southeastern Coastal Plain soils. Soil Science. 172(8):651-658. (PDF; 500 KB)
Caesar, T., Caesar, A.J., Gaskin, J.F., Sainju, U.M., Busscher, W.J. 2007. Taxonomic diversity of predominant culturable bacteria associated with microaggregates from two different agroecosystems and their ability to aggregate soil in vitro. Applied Soil Ecology. 36(1):10–21. (PDF; 535 KB)
Caesar, T., Lartey, R.T., Shelver, W.L. 2007. Enzyme-linked immunosorbent assay for Cercospora beticola in soil. Journal of Sugarbeet Research. 44:51-70. (PDF; 8344KB)
Lartey, R.T., Caesar, T., Hanson, S.L., Iversen, W.M., and Evans, R.G. 2007. Detection of Cercospora beticola by PCR in amended and naturally infested field soil. Journal of sugar beet research. 44(3-4): 160-161. (PDF; 1191 KB)
Lartey, R.T., Caesar, T., Hanson, S.L., Iversen, W.M., Evans, R.G. 2007. Detection of cercospora beticola by PCR in amended and naturally infested field soil. In: Proceedings of the 34th Biennial Meeting of the American Society of Sugarbeet Technologists, February 28-Mark 3, 2007, Salt Lake City, Utah. 34: 211-216. (PDF; 4744 KB)
Lartey, R.T., Caesar-Tonthat, T., Iversen, W.M., Hanson, S., and Evans, R.G. 2007. Survey of field soils for Cercospora beticola by PCR and ELISA. Journal of sugar beet research. 44(3-4): 49. (PDF; 619KB)
Lartey, R.T., Caesar-Tonthat, T., Iversen, W.M., Hanson, S., and Evans, R.G. 2007. Survey of field soils for Cercospora beticola by PCR and ELISA. Proceedings. 34: 164-148. (PDF; 3242 KB)
Sainju, U.M., Caesar, T., Lenssen, A.W., Evans, R.G., Kolberg, R.L. 2007. Long-term tillage frequency and cropping intensity effects on dryland residue and soil carbon fractions. Soil Science Society of America Journal. 71(6):1730-1739. (PDF; 520 KB)
Sainju, U.M., Lenssen, A.W., Caesar, T., Waddell, J.T. 2007. Dryland plant biomass and soil carbon and nitrogen pools as influenced by tillage and crop rotation. Soil and Tillage Research. 93:452-461.
Sainju, U.M., Lenssen, A.W., Caesar, T., Waddell, J.T. 2006. Carbon sequestration in dryland soils and plant residue as influenced by tillage and crop rotation. Journal of Environmental Quality. 35:1341-1347. (PDF; 191 KB)
Busscher, W., Novak, J., and Caesar, T. 2006. Organic Matter and Polyacrylamide Amendment of Norfolk Loamy Sand. Soil & Tillage Research Journal. 93:171-178. (PDF; 234 KB)
Novak, J., Szogi, A., Watts, D., Basta, N., Dayton, E., and Caesar, T. 2006. Use of Water Treatment Residuals As a Best Management Practice to Bind P in Upland and Wetland Ecosystems. Abstract, International Soil Science Congress Proceedings.
Sainju, U.M., Lenssen, A., Caesar-TonThat, T., and Waddell, J. 2006. Tillage and crop rotation effects on dryland soil and residue carbon and nitrogen. Soil Science Society of America Journal. 70:668-678. (PDF; 188 KB)
Holtz, B.A., Mckenry, M.V., Caesar, T. 2005. Wood chipping and its effect on soil and petiole nutrients, soil aggregation, water infiltration, nematodes and basidiomycetes populations. Mediterranean Options. 63:247-254.
Lartey, R.T., Caesar, T., Caesar, A.J., Shelver, W.L., Sol, N.I., Bergman, J.W. 2005. Safflower: a new host of Cercospora beticola. Plant Disease. 89(8):797-801. (PDF; 320 KB)
Lartey, R.T., Caesar, T., Sol, N.I., Goshroy, S. 2005. Additional evidence of Safflower (Carthamus Tinctorius) as an alternate host to Cercospora Beticola. In: Proceedings from the 33rd Biennial Meeting Agriculture. American Society of Sugarbeet Technologists, March 2-5, 2005, Palm Springs, California. P. 144-150.
Pikul Jr, J.L., Johnson, J.M., Wright, S.E., Caesar, T., Ellsbury, M.M. 2005. Soil Organic Matter and Aggregate Stability Affected by Tillage. E.A. Ghabbour and G. Davies (Eds) Humic Substances: Molecular Details and Applications in Land and Water Conservation. Taylor and Francis, Inc. New York. P. 243-258. (PDF: 5005 KB)
Sainju, U., Lenssen, A., Evans, R., Caesar, T., and Waddell, J. 2005. Tillage, Crop Rotations, and Cultural Practices Effects on Dryland Soil and Crop Residue Carbon and Nitrogen. Abstract, International Conference on Sustainable Agriculture for Food, Energy and Industry.
Wuest, S.B., Caesar-Tonthat, T.C., Wright, S.F., Williams, J.D. 2005. Organic Matter Addition, N, and Residue Burning Effects on Infiltration, Biological, and Physical Properties of An Intensively Tilled Silt-Loam Soil. Soil & Tillage Research 84 (2005) 154-167. (PDF; 382KB)
Caesar, T., Caesar, A., and Sainju, U. 2004. Isolation, Identification, and Characterization of Soil Aggregating Bacteria in Soil Microaggregates. Abstracts, American Society of Agronomy Meetings.
Holtz, B.A., Mckenry, M.V., Caesar, T. 2004. Wood chipping almond brush and its effect on the almond rhizosphere, soil aggregation and soil nutrients. Acta Hort. (ISHS) 638:127-137.
Lartey, R.T., Caesar, T., Caesar, A.J., Shelver, W.L., Sol, N.I. 2004. Safflower: An Alternate Host of Cercospora Beticola. Phytopathology. 94(6):s57.
Lartey, R.T., Weiland, J.J., Caesar, T., Bucklin Comiskey, S.A. 2003. A PCR Protocol for Rapid Detection of Cercospora Beticola in Infected Sugar Beet Tissues. Journal of Sugarbeet Research. 40: 1-10. (PDF; 5067KB)
Lartey, R. T., Weiland, J. J., Caesar-TonThat, T. C., and Bucklin-Comiskey, S. A. 2003. A PCR protocol for rapid detection of Cercospora beticola in injected plant tissues. Journal of Sugar Beet Research 49:1-2.
Pikul Jr, J.L., Johnson, J.M., Caesar, T., Wright, S.E., Ellsbury, M.M. 2003. Soil Organic Matter and Aggregate Stability Affected by Tillage in the Northern Corn Belt. Natural Organic Matter in Soils and Water North Central Region Symposium. P. 20.
Pikul Jr, J.L., Wright, S.E., Johnson, J.M., Caesar, T., Ellsbury, M.M. 2003. Tillage Effects on Distribution of Organic Matter among Soil Aggregate CLASSES.[CD-ROM]. Asa-Cssa-Sssa Annual Meeting Abstracts. Madison, Wisconsin.
Caesar-TonThat, T. C. 2002. Soil binding properties of mucilage produced by a basidiomycete fungus in a model system. Mycological Research 106:930-937.
Holtz, B. A., McKenry, M. V., and Caesar-TonThat, T. C. Wood chipping almond brush and its effect on soil and petiole nutrients, soil aggregation, water infiltration and nematode and basidiomycete populations. Mediterranean Options (in press).
Holtz, B.A., McKenry, M.V., and Caesar-TonThat, T. C. 2002. Wood chipping almond brush and its effect on the almond rhizosphere, soil aggregation, and soil nutrients. Acta Horticulture (in press).
Caesar-TonThat, T. C., W. Shelver, R. G. Thorn, and V. L. Cochran, 2001. Generation of antibodies for soil-aggregating basidiomycete detection to determine soil quality. Applied Soil Ecology 18:99-116.
Caesar-TonThat, T. C., and V. L. Cochran. 2001. Role of saprophytic basidiomycete soil fungus in aggregate stability, p. 575-579. In: D. E. Stott, R. H. Mohtar, and G. C. Steinhardt (eds). Sustaining the Global Farm- Selected papers from the 10th International Soil Conservation Organization Meeting, May 24-29, 1999, West Lafayette, IN.
Cochran V. L. and Caesar-TonThat, T. C. 2001. Soil quality factors and grain yields 16 years after top soil removal. (Submitted paper).
Caesar-TonThat, T. C., and V. L. Cochran. 2000. Soil aggregate stabilization by a saprophytic lignin decomposing basidiomycete fungus. I. Microbiological aspects. Biology and Fertility of Soils 32:374-380.
Frederick, B., T. C. Caesar-TonThat, M. H. Wheeler, K. B. Sheehan, W. A. Edens and J. M. Henson. 1999. Isolation and characterization of Gaeumannomyces graminis var. graminis melanin mutants. Mycological Research 103:99-110.
Money, N. P., B. Frederick, T. C. Caesar-TonThat, and J. M. Henson. 1998. Melanin synthesis is associated with changes in hyphopodia turgo, permeability, and wall rigidity in Gaeumannomyces graminis var. graminis. Fungal Genetics Biology 24:240-251.
Caesar-TonThat, T. C., and J. E. Cutler. 1997. Enhancement of mouse neutrophil candidacidal activity by a protective monoclonal antibody. Infection Immunity 65:5354-5357.
Caesar-TonThat, T. C., F. Van Ommen Kloeke, G. G. Geesey, and J. M. Henson. 1995. Melanin production by a filamentous soil fungi in response to copper and localization of copper sulfide by sulfide-silver staining. Applied and Environmental Microbiology 61:1968-1975.
Henson, J. M., and T. C. Caesar-TonThat. 1995. Mitochondrial plasmids of Gaeumannomyces-Phialophora fungi and their detection by primed, in situ fluorescent labelling. Experimental Mycology 19:263-274.
Caesar-TonThat, and D. C. Sands. 1994. Oil and absorbent coated granules containing encapsulated living organisms for controlling agricultural pests. US Patent number: 5,358,863.
Caesar-TonThat, T. C., W. E. Dyer, P. C. Quimby, and S. S. Rosenthal. 1993. Formulation of an endoparasitic nematode Subanguina picridis Brzeski, a biocontrol agent for Russian knapweed (Acroptilon repens (L.) (DC). Biological Control 5:262-266. Quimby, Jr. P. C., J. L. Birdsall, A. J. Caesar, W. J. Connick Jr., C. D. Boyette, T. C.
Liebman, J. A., T. C. Caesar-TonThat, and L. Epstein. 1993. Ultrastructure of Cochliobolus victoriae conidia incubated on fungistatic soil. Mycological Research 97:1419-1429.
Caesar-TonThat, T. C., W. E. Dyer, S. S. Rosenthal, P. C. Quimby, and S. W. Chaney. 1992. Cooperative research efforts to develop the use of a nematode for Russian knapweed biocontrol. The Georges Wright Forum 9 (1):45-48.
Turian, G., F. Barja, and T. C. Caesar-TonThat. 1992. Nucleolar dense granules in cytochalasin-treated conidia of Neurospora crassa. Cell Biology International Reports. 16:1265-1266.
Caesar-TonThat, T. C., and L. Epstein. 1990. Freeze-substituted fungal cells of Nectria haematococca: a comparison of the macroconidial walls of the adhesion-competent wild-type with an adhesion-reduced mutant. Experimental Mycology 15:193-205.
Caesar-TonThat, T. C., C. Rossier, F. Barja, G. Turian, and U. P. Roos. 1988. Induction of multiple germ tubes in Neurospora crassa by antitubulin agents. European Journal of Cell Biology 46:68-79.
Caesar-TonThat, T. C., K. Hoang Van, G. Turian, and H. C. Hoch. 1987. Isolation and characterization of coated vesicles from filamentous fungi. European Journal of Cell Biology 43:189-194.
Turian, G., and T. C. Caesar-TonThat. 1987. Multipolar germination of conditionally produced conidia in an "amycelial" mutant of Neurospora crassa. Journal General Applied Microbiology 33:543-545.
Turian, G., T. C. TonThat, and R. Ortega-Perez. 1985. Acid tip linear growth in fungi: requirements for H+/Ca2+ inverse gradients in cytoskeleton integrity. Botanica Helvetica 95:311-322.
Turian, G., C.-L. Geisler, and T. C. TonThat. 1985. Ribosomal exclusion from the most acidic tip-zone of fungal hyphae. Microbios Letters 30:19-22.
TonThat, T. C., and G. Turian. 1984. High-resolution autoradiography of nuclear modifications during and after heat induction of microcyclic conidiation in Neurospora crassa. Protoplasma 120:165-171.
TonThat, T. C., M. Michea-Hamzehpour, and G. Turian. 1983. Ultrastuctural demonstration of loss and recovery of cytochrome oxidase activity during and after heat-induction of microcyclic conidiation in Neurospora crassa. Protoplasma 116:149-154.
TonThat, T. C., G. Turian, J. Fakan, and A. Gautier. 1981. Ultrastructural cytochemistry of perinucleolar dense spots in heat-treated macroconidia of Neurospora crassa. European Journal of Cell Biology 24:317-319.
Michea-Hamzehpour, M., F. Grange, T. C. TonThat, and G. Turian. 1980. Heat-induced changes in respiratory pathway and mitochondrial structure during microcyclic conidiation. Archives Microbiology 125:53-58.
Michea-Hamzehpour, M., R. Ortega-Perez, A. Rougemont, F. Vanderhaeghe, E. Khandjian, T. C. TonThat, and G. Turian. 1979. Isolation of two mitochondrial populations with differential hydroxamate sensitivity from the poky mutant of Neurospora crassa. FEMS Microbiology Letters 6:213-218.
TonThat, T. C., and G. Turian. 1978. Ultrastructural study of microcyclic macroconidiation in Neurospora crassa. Archives Microbiology 125:53-58.
Rossier, C., T. C. TonThat, and G. Turian. 1977. Microcyclic conidiation in Neurospora crassa. Experimental Mycology 1:52-62.