An increasing number of crops commercially grown today are genetically modified (GM) to resist insect pests and/or tolerate herbicides. Although Bt corn is one of the most commonly grown GM crops in the United States, little is known about its effects on the long-term health of soils. Although there are many benefits to using biotechnology in agriculture, such as potentially reducing insecticide use, there may be unintended side effects as welldoes GM corn impact non-target soil organisms, such as arbuscular mycorrhizal fungi, or affect plants subsequently grown in the same field?
Bt corn is genetically engineered to express insecticidal toxins derived from a soil bacterium, Bacillus thuringiensis, to protect it against common agricultural pests such as the corn root worm and European corn borer. Tanya Cheeke and her colleagues (at Portland State University, Oregon) were interested in determining whether the cultivation of Bt corn has a negative effect on arbuscular mycorrhizal fungal colonization of Bt corn or of crops subsequently planted in the same soil. They published their findings in a recent issue of the American Journal of Botany (http://www.amjbot.org/content/99/4/700.full).
Arbuscular mycorrhizal fungi (AMF) are ubiquitous microscopic soil fungi that form symbiotic relationships with the roots of most plants. Plants supply the fungi with carbon, and the fungi increase the host plant's ability to uptake nutrients and water from the surrounding soil.
"Because these fungi rely on a plant host for nutrition and reproduction, they may be sensitive to genetic changes within a plant, such as insect-resistant Bt corn," stated Cheeke.
By experimentally planting seeds from several different lines of both Bt corn and non-Bt corn, and using local agricultural soil containing native mycorrhizal fungi, the authors were able to simulate what might happen naturally i
|Contact: Richard Hund|
American Journal of Botany