Roundup Ready Kentucky Bluegrass: Benefits and Risks

April 28, 2014

By Garett Heineck

In the summer of 2011 Scott’s turf company announced the release of the first genetically engineered turfgrass. Scott’s chose to genetically engineer Kentucky bluegrass, a widely used lawn grass, to be resistant to glyphosate, which is the active ingredient in the common non-selective herbicide Roundup. This newest addition to the list of “Roundup Ready” plant species has been the focus of much media attention. Although Roundup Ready technology has been around since the mid 1990’s, species containing the gene have been limited to agricultural crops, including corn, cotton, and soybeans. The National Agricultural Statistics Service reported that in 2013 the percent total acreage of genetically engineered corn, soybean and cotton was 90%, 93% and 90%, respectively. The widespread use of the Roundup Ready trait originates from the low cost, effectiveness, and relative safety of glyphosate. However, the heavy use of this product is not without obstacles. The emergence of glyphosate resistant weeds and pollen contamination of non-genetically engineered plants has been an ongoing concern in agriculture. Before deciding to either condemn or praise Roundup Ready Kentucky bluegrass (RRKB) it is important to consider the risks and benefits of genetic engineering in turf.

A basic understanding of genetic engineering is essential before framing an opinion about Roundup Ready turfgrass. A common misconception is that genetic modification is synonymous with genetic engineering. Genetic modification can be simplified as selection of plants to increase their utility for humans. The process of genetic modification has been carried out for thousands of years, whereas genetic engineering is a relatively new technology that became popular in the mid 1980’s. Genetic engineering infers the insertion of a particular gene (transgene) whose function is known in a plant where it was not previously expressed. Gene insertion can be carried out in several ways, and commonly involves the use of a gene gun or a biological vector such as Agrobacterium tumifacians, which is a common plant pest. Because the effect and safety of these transgenes is not always known, the US government enlisted several agencies to oversee the issues surrounding the safety of genetically engineered crops.

The three agencies appointed to regulating genetically engineered (GE) crops are the United States Department of Agriculture (USDA), Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA). The USDA regulates GE crops by controlling plant movement, plant pests and noxious weeds (McHughen and Smyth, 2008). The EPA regulates GE crops, which contain plant-incorporated pesticides (McHughen and Smyth, 2008). Finally the FDA regulates the safety of GE crops, used for food and feed purposes (McHughen and Smyth, 2008). Before a GE crop can be sold to the public one or all of these agencies will be involved to determine the risks of the crop.

Considerable media attention surrounding RRKB has been focused on the dubious nature of its release, as Scott’s Company was able to circumvent all government regulation concerning GE crops. This sidestepping was accomplished because of the nature of the use of turfgrass and the method of transgene insertion. Any plant which used Agrobactium (a plant pest) as a gene vector is regulated by the USDA, but Scotts used a gene gun and a Roundup Ready gene from a non-plant pest to achieve glyphosate resistance (Wang and Brummer, 2012). Any plant incorporated pesticide, such as the well-known Bt trait, is regulated by the EPA. Scott’s RRKB only contains the Roundup Ready gene which does not express pesticides.  Finally, turfgrass is not a food or feed product, which are regulated by the FDA. For the aforementioned reasons the US government has no regulatory authority over Roundup Ready Kentucky bluegrass and Scott’s is free to release RRKB as it would any other non-GE variety.

RRKB is not consumed for food, does not express pesticides and is not considered a plant pest. So what are the possible risks of GE turfgrass? Hypothesized risks involve pollen contamination, increased risk of glyphosate resistant weeds, and escape from intended area of use. In turf species pollen contamination can be considered the greatest hazard, which occurs when pollen from a GE crop fertilizes a non-GE crop (Mallory-Smith and Zapiola 2008). This can be an issue for seed producers trying to grow seed for organic growers or consumers who wish to have non-GE turfgrass. Crops in which pollen contamination has been a problem include Roundup Ready alfalfa, sugar beet and creeping bentgrass (Mallory-Smith and Zapiola, 2008). Also, cross-fertilization can be an issue if there are any native plants, which are sexually compatible with the GE plant. In the case of RRKB this could be a potential problem because of the diverse nature of the genre (Poa) to which Kentucky bluegrass belongs. There are approximately 300 species in the Poa genus some of which are considered native to the US (Wipff, 2002).

With all of the previously examined regulations and risks surrounding GE plants, why are they so popular? One reason is that GE has the potential to increase the utility of species in ways that would be otherwise near impossible. GE has been shown to enable plants to better protect themselves from disease and insect pressure, increases resistance to drought and heat stress and allows resistance to non-selective herbicides like glyphosate. The real question is how important is RRKB in light of the potential risks associated with its release? RRKB will allow for production of weed free lawns with little knowledge of alternative management practices and species selection while using a low risk herbicide (assuming no glyphosate resistant weeds.) However, using the correct species and variety selection in conjunction with best management practices have been shown to yield high quality weed free lawns. The key deciding factor is the amount of time and energy the public is willing to put into education and home lawn management. Resources on species selection and appropriate management practices for different turfgrass situations are available through UMN Turfgrass Extension.

References:
-Mallory-Smith, Carol, and Maria Zapiola 2008 Gene Flow from Glyphosate-Resistant Crops. Pest Management Science 64(4): 428–440.
-McHughen, Alan, and Stuart Smyth 2008 US Regulatory System for Genetically Modified [genetically Modified Organism (GMO), rDNA or Transgenic] Crop Cultivars. Plant Biotechnology Journal 6(1): 2–12.
-Wang, Zeng-Yu, and E. Charles Brummer 2012 Is Genetic Engineering Ever Going to Take off in Forage, Turf and Bioenergy Crop Breeding? Annals of Botany 110(6): 1317–1325.
-Wipff, Joseph K. 2002 Gene Flow in Turf and Forage Grasses (Poaceae). In Proceedings of Scientific Methods Workshop: Ecological and Agronomic Consequences of Gene Flow from Transgenic Crops to Wild Relatives Pp. 143–161. http://www.biosci.ohio-state.edu/~asnowlab/Proceedings.pdf#page=145, accessed February 14, 2014.