Reading #3 - Herbicide resistance and the shikimate pathway (due on Mon Oct 23rd)

News Focus, Science Vol 316 (2006)

Pest Management Science 68: 3–9 (2012) Shaner et al.

These two papers are an interesting illustration of how genetically modified plants working 'too well'.... Plant molecular biologists created glyphosate-resistant crop plants through genetic engineering, and weeds have evolved the same trait. Read the Science (2006) article first, then Shaner et al. (2012).

Please jot down your answers to these questions to help you read the papers.

1. What properties make glyphosate such a useful (potent but relatively safe) herbicide?

2. Are there benefits to using genetically engineered glyphosate-resistant crop plants for agriculture?

3. What three mechanisms are discussed as potential mechanisms of glyphosate resistance in weeds, and which two of these have been documented.

4. How many amino acid residues need to be changed to get a glyphosate-resistant ESPS enzyme?

5. What should be done (or should have been done...) to prevent emergence of herbicide resistant weeds?