Research TopicsDepartment of Plant Pathology
Ph.D. (1973) University of Rochester
Research Topics
Research Interests
The research efforts in this laboratory fall into three areas. The first area involves development of an improved agrocin 84 control system for crown gall disease. To do this, we must have a better understanding of agrocin 84 production by A. radiobacter, and the molecular basis for sensitivity of A. tumefaciens to agrocin. We are currently dissecting the pathway for agrocin biosynthesis and the genes that are responsible for transfer to other Agrobacteria. We have constructed plasmids which overproduce agrocin 84 and which are unable to transfer to other strains. To reduce the occurrence of resistance to Agrocin 84 which has arisen in some localities, we will attempt to construct field control agents which produce two or more agrocins, each with a different specificity of killing.
The second long term project in the laboratory is to understand how Agrobacterium tumefaciens interacts with plant cells to induce crown gall tumors. Specifically we are studying the regulatory relationships between Ti plasmid determinants for opine degradation and conjugal transfer. The loci for these functions have been cloned and structure/function relationships are being studied.
The third area of research is to engineer a beneficial bacteria-plant system where the interaction is stable and as long-lived as is necessary to realize the protective or enhancing effect. The strategy which we employ is to obtain a bacterial partner which specifically and efficiently utilizes a nutritional source produced by the plant, but which is not available to competing soil microflora. We will engineer the bacterial partner to utilize compounds of the mannityl opine family and the plant partner will be engineered for opine production by disarmed T-DNA.
The Agrobacterium genes for mannityl opine catabolism have been cloned and vector systems for their efficient transfer and expression in Rhizobium, Azotobacter, and Pseudomonas species are being constructed. We are also developing and testing a binary, disarmed T-DNA vector for constructing opine-producing plants. In collaboration with other laboratories, we hope to transform soybean callus and other potential plant hosts. Opine-producing normal plants will be inoculated with the engineered bacterial species and field-tested to see if a competitive bacteria-plant interaction can be established.
Key Words
Recombinant DNA, Introduction of DNA into Plant Cells, Microbial
Physiology, Plant Cell and/or Tissue Culture, Plant/Pathogen Interactions
Current Research Funding
USDA, BRDC, Illinois Soybean Program Operating
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