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A Simple Twist of Evolution
MADISON, WI, August 11, 2008 -- An interactive web lesson teaches students about fatty acids. The web lesson, developed by William E. Dyer, Montana State University, has the seal of approval by the Journal of Natural Resources and Life Sciences Education.
"This online eLesson is designed to teach students about the role fatty acids play in a plant's life, and where herbicides block the pathway," says Dyer.
How some plants resist these herbicides is described in the lesson, written to target the educational needs of upper-level undergraduate students and graduate students. A set of quiz questions focusing on these objectives is a part of the lesson.
In plants, fatty acids are so important that they have two parallel biosynthetic pathways that are similar to those found in animals and bacteria. Plants also process fatty acids into waxes and other protective compounds. Obviously, a chemical that blocks this pathway (such as an herbicide) should be lethal to all plants. However, a tiny alteration in the DNA sequence of the first enzyme in the pathway makes some grasses completely susceptible to these herbicides, while other grasses and broadleaf plants are not harmed.
According to Dyer, "This very small evolutionary change allows farmers to kill grassy weeds without affecting their crops."
Development of the lesson was supported in part by the Montana Agricultural Experiment Station, Montana State University, and the Western Society of Weed Science.