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Walt Ream
Professor, Microbiology
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RESEARCH:
Agrobacterium tumefaciens is the only prokaryote known to transfer genes to a eukaryote. Agrobacterium is important both as a plant pathogen and as a means to introduce novel genes into plants. Our laboratory studies the DNA-protein interactions necessary to transfer tumor-inducing genes from Agrobacterium into plant cells.
During tumor induction, A. tumefaciens transfers specific bacterial genes into plant cells where these genes enter the nucleus and integrate into plant nuclear DNA. Plant tumor cells express transferred genes responsible for tumorous growth a nd for production of novel compounds which the tumor-inducing bacteria use as nutrients. Thus, A. tumefaciens engineers plant cells to grow rapidly, and produce nutrients for the bacteria.
Transfer of genes between these bacteria and plants requires the DNA to cross the plant nuclear membrane. Two bacterial virulence proteins attach to the transferred DNA and accompany it into plant cells. We discovered that one of these proteins helps pilo t bacterial DNA across the nuclear membrane and into the nucleus. The other protein appears to mediate integration of bacterial DNA into the plant genome. Our work will continue to focus on nuclear transport and DNA integration in plants.