Speaker: Wilfried T. Foadey
Candidate for Bachelor of Science in Biology
Time: 6:10 PM
Place: Trustee Hall 113
Supervisor: Dr. Gregory Heck
Title: Isolation and Comparison of Selected Plant EPSPS Coding Regions to Better Understand the Evolution of Glyphosate Resistance

Abstract: Some biotypes of plant species appear to be naturally resistant to glyphosate, the active ingredient of Roundup herbicide (Perez and Kogan, 2002; Bearson et al., 2002). Glyphosate inhibits EPSPS, and thereby, blocks the shikimate pathway, which is essential for plant growth and development (Ng et al. 2003). Some plant species, such as a biotype of Eleusine indica in Malaysia, are resistant to herbicides, causing serious problems for modern agriculture (Bearson et al., 2002; Richter, Zweger, and Bottcher, 2002). Studies on Eleusine indica reveal an amino acid substitution in EPSPS that produced a resistant biotype; the first evidence for an altered EPSPS enzyme that resulted in glyphosate resistance (Bearson et al., 2002). The observation in Eleusine indica suggests that not all plant EPSPS are identical, that a variety that impacts the active site may exist in the plant kingdom. To determine the diversity of higher plant EPSPSs, we isolated the sequence for EPSPS coding regions for cloning, and comparison with Aro A1, a known EPSPS. Successful sampling and examination of the active sites of isolated EPSPS coding regions in Conyza canadensis, Helianthus salicifoluis, Sarracenia purpurea, and Asimina triloba show a overall similarity to Aro A1. We found no indication of a resistant EPSPS enzyme.