Bacillus Cereus UW85 and Tomato Plants: A Biological Control Model SystemEPA Grant Number: U915617
Title: Bacillus Cereus UW85 and Tomato Plants: A Biological Control Model System
Investigators: Dunn, Anne K.
Institution: University of Wisconsin Madison
EPA Project Officer: Hahn, Intaek
Project Period: May 1, 1999 through May 1, 2002
Project Amount: $75,259
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Fellowship - Life Sciences , Academic Fellowships , Biology/Life Sciences
The objective of this research project is to better understand the relationship between the bacterium Bacillus (B.) cereus UW85 and the plants it associates with through identification of bacterial genes that are regulated in the presence of plant compounds.
An experimental system has been designed to study the interactions between a Gram-positive biological control organism, a plant host, and a pathogen that uses recombinant inbred lines of tomato, B. cereus UW85, and the plant pathogen, Pythium torulosum Coker and Paterson. Tomato seed exudate has been chosen as the source of plant compounds because the seed and seedling are most susceptible to infection by Pythium during seed germination and radicle formation. To identify DNA sequences of B. cereus UW85 that contain promoters or promoter-like sequences regulated in the presence of tomato seed exudate, a promoter-trap plasmid has been constructed for use in B. cereus, pAD123. pAD123 contains a promoterless gene that encodes a mutant version of the green fluorescent protein, GFPmut3a, that is optimized for fluorescence-activated cell sorting (FACS). A library has been constructed in pAD123, which consists of 34,000 clones containing 1-3 kb chromosomal DNA fragments from UW85. By adapting a cell-sorting protocol for use with B. cereus, it is possible to rapidly screen the library for regulation of GFP expression when the clones are exposed to compounds originating from a plant host, tomato. Clones isolated in the screening procedure will be further characterized through sequencing of the DNA inserts and determination of the biological function of regulated genes in the plant-microbe interaction.
The study will provide a better understanding of Gram-positive bacteria and their plant hosts, which will improve the efficiency and reliability of biological control as an environmentally safe supplement to chemical pesticides.