Biology Reference
In-Depth Information
Table 6.1.
Potentially detrimental impacts of genetically modified crop
plants. (Modified from Dale et al. 2002.)
D
IRECT IMPACTS
• Impacts on nontarget organisms
-Effects of Bt and other endotoxins on nonpest animals
-Effects of pesticidal toxins on soil organisms and processes
• Altered crop plant behavior
-Increased postharvest persistence in cropland
-Invasiveness in natural habitats
I
NDIRECT IMPACTS
• Gene flow to noncrop plants and selection for transgenic characteristics
-Transgenic resistance to one or more herbicides
-Transgenic biotic or abiotic stress resistance
• Evolutionary influences of increased herbicide and other pesticide use
-Selection for herbicide resistance by noncrop plants
-Selection for animal pest resistance to Bt and other endotoxins
• Ecological effects of altered pesticide use patterns
-Effects of altered herbicide use on noncrop plant species and
communities
-Effects of altered pesticide use on nonpest animal species and
communities
been approved for distribution in North America and some other areas:
oilseed rape, cotton, maize, potato, soybean, sugar beet, tobacco, and
tomato (Hilbeck 2001). Transgenic maize (
Zea mays
), oilseed rape (
Bras-
sica napus
), and cotton (
Gossypium hirsutum
) are all widely cultivated, espe-
cially in the Americas, and are all capable of interbreeding with wild rel-
atives. Many more transgenic crop plants are being tested experimentally
and are likely to be approved for release in the near future.
To date, transgenes from crop plants do not appear to have become
established in noncrop races or species. Hybridization of different crop
races of oilseed rape and possibly maize, however, has been shown to lead
to the transfer of transgenes (Ellstrand 2001). In the case of oilseed rape,
plants that combined transgenic resistance to three herbicides were found
in a field situation in Alberta, Canada.Two sequential hybridization events
were required to produce these plants from the individual oilseed rape
varieties containing individual herbicide resistance genes.Thus, it appears
to be only a matter of time until transgenes become established in some
noncrop plants.
