There has been much recent interest in the development of crops that are tolerant or resistant to the herbicide glyphosate. Glyphosate is a nonselective systemic herbicide that can control many annual and perennial weeds regardless of their size, a characteristic atypical of most selective herbicides used in crop production. Crop tolerance to glyphosate would be beneficial as it would provide growers, for the first time, the opportunity to control almost all weeds with a single herbicide application.