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Future Possible Genetically Engineered Crops and Traits and Their Potential Environmental Impacts
- Michigan State University Press
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47 Future Possible Genetically Engineered Crops and Traits and Their Potential Environmental Impacts Rebecca Grumet, LaReesa Wolfenbarger, and Alejandra Ferenczi The “first wave” of genetically engineered (GE) crops was focused nearly exclusively on very high acreage crops and a handful of readily cloned, highly effective genes conferring insect resistance and herbicide tolerance (table 1).There were also a few instances of genetically engineered virus resistance in squash and papaya, but together they have accounted for less than 0.1% of transgenic acreage (Brookes and Barfoot 2006; James 2006). Table 1. Genetically Engineered (GE) Crops Produced during the First Decade of Commercial GE Crop Production, 1996– 2006 Crop % GE crop production Trait First year of production Soybean 62% Herbicide resistance 1996 Corn 22% Insect resistance 1996 Herbicide resistance 1997 Cotton 11% Insect resistance 1996 Herbicide resistance 1997 Canola 5% Herbicide resistance 1996 Low- acreage crops Potato Insect resistance 1996– 2000* Alfalfa Herbicide resistance 2006 Papaya Virus resistance 1999 Squash Virus resistance 1996 Sources: James 2007; Brookes and Barfoot 2006. * The GE potato was only produced for a short period of time before it was removed from the market. 48| Grumet, Wolfenbarger, and Ferenczi The next decade of GE crops promises to bring a host of new crops, genes, traits, and locations , and with it, a broader range of environmental safety questions. The increase in variety is due to continually more sophisticated molecular genetic and genomic technologies that have expanded our ability to obtain new genes of value, and an increasing number of public-and private- sector groups developing GE crops in both developed and developing countries. In some cases we will see use of familiar genes in new crops, such as herbicide resistance in sugar beet in the United States and Bt genes in eggplant (brinjal), which is undergoing development in India, Bangladesh, and the Philippines (Ramanujan 2007). In other cases, there will be new kinds of genes and traits in previously engineered crops, such as enhanced drought stress resistance in corn, or combinations of new genes and new GE crops, such as pro- vitamin A enhanced rice. Examples of new crops and traits in development, based on recorded field trials in the United States in 2007, are summarized in tables 2 and 3. Similarly expanded lists of crops and traits are also being developed in other locations. For example, Argentina has more than 140 transgenic events under evaluation, including crops engineered with new traits such as drought tolerance and modified oil content (table 4). Environmental safety considerations for GE crops vary with crop, gene, trait, and location and result from a complex interplay of each of the factors (figure 1). For example, modified nutritional content is less likely to provide a selective advantage to the crop or interfertile relative than is increased drought stress tolerance. In addition, the same gene or trait may have different potential impacts in different crops, depending on outcrossing rates of the crop, weediness of compatible relatives, or possible interaction with other traits in the crop that may lead to enhanced competitiveness of the crop in the wild (Hancock 2003). As mentioned in previous chapters, a given trait- crop combination could have different potential impacts in Table 2. Permits and Acknowledgments for Crops or Species Tested in Field Trials in the United States in 2007 More than 10 trials No. Trials Other crops/species (no. trials) Corn Soybean Cotton Loblolly pine Alfalfa Tobacco Potato Rapeseed Poplar Tomato Wheat Eucalyptus 255 141 48 27 24 23 19 19 15 11 11 11 Commodity and subsistence crops Barley (8), cassava (6), rice (6), sugarcane (6), peanut (5), safflower (4), sugarbeet (4), sorghum (3), cowpea (1), drybean (1), guayule (1), sweetpotato (1) Fruits, vegetables Grape (9), apple (5), grapefruit (5), papaya (3), plum (2), banana (1), melon (1), onion (1) Trees and shrubs Cottonwood (9), aspen (2), chestnut (2), sweetgum (2), walnut (1) Grasses Bahia grass (1), bent grass (1), Bermuda grass (1) Ornamentals Antherium (2), camelia (2), marigold (1), rose (1) Source: USDA-APHIS records, http://www.nbiap.vt.edu. [3.91.17.78] Project MUSE (2024-03-29 12:31 GMT) Table 3. Types of Traits Tested in Field Trials of Transgenic Plants in the United States (permits and acknowledgments issued) and Argentina in 2007 and 2001 More than 10 trials in the U.S. Trials in Argentina Other traits tested in the U.S. (and Argentina) in 2007 2007 2001 2007 2001 Product quality Altered lignin (8), reduced polyphenols (7), color/ pigment (6), flavor (3), fiber...