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Ok. I know that when you are testing and developing new GMO products, the seeds and pollen have to be strictly controlled. How do you prevent cross-pollination from bees/other insects or critters, or even prevent microorganisms and nematodes from getting out of a controlled environment? I'm no scientist, but I know that I track everything everywhere in my own garden, from aphids to spider mites to fungi to... well, whatever decides it wants to hitch a ride from point A to point B!

Submitted by: fezmarie73


Expert response from Michael Weeks

U.S. Registration Manager, United States, BASF

Thursday, 06/11/2014 15:28

In the United States, field trials of new GMO crops are regulated by the Biotechnology Regulatory Service (BRS), which is a part of the U.S. Department of Agriculture’s (USDA’s) Animal and Plant Health Inspection Service (APHIS). In order to have a field trial of a regulated GMO crop, the developer or researcher must have a protocol for minimizing cross-pollination to compatible plants that are not part of the field trial.

USDA APHIS BRS maintains guidance on how GMO crop researchers and product developers should reproductively isolate the most common crops field tested in the United States. This guidance document can be found on the USDA APHIS BRS website and is referred to as “Minimum Separation Distances to Be Used for Confined Field Tests of Certain Genetically Engineered Plants.” As the title of this USDA guidance document indicates, a common approach to minimizing pollen movement to a reproductively compatible recipient plant is by planting the field trial at a defined “separation distance” from any other receptive plants, either crops or weeds. This distance varies depending on the nature of the crop (e.g., heaviness of the pollen, prevalence of insect pollination, flower shape, tendency toward self- vs. open pollination).

For example, in soybeans, the timing of pollen development, the flower opening and the structure of the flower result in cross-pollination rates of less than 1 percent for plants in adjacent rows (Caviness, 1966). Because of the low level of cross-pollination, soybeans require an isolation distance of only 10 feet from non-GMO soybeans to prevent accidental mechanical mixing during field operations. Cotton, which is more prone to cross-pollination by insects, requires greater isolation distances than soybeans. Cross-pollination rates in cotton vary based on weather conditions and the species of pollinators present. Isolation distances of 10 meters have been shown to bring cross-pollination rates to under  1 percent (Van Deynze et al., 2005). Isolation distances of 200 meters are recommended by OECD for the production of certified commercial seed (OECD, 2008), which is consistent with the USDA’s minimum requirements for regulated GMO field trials.

Another method suitable to some insect-pollinated crops, such as cotton, is the use of a “pollen trap” (Simpson and Duncan, 1956). In cotton crops, a pollen trap is a planted border of cotton around the field trial that is planted at the same time as the regulated GMO cotton trial and is a variety that will develop and flower at the same time as the GMO field trial. Pollinators that come into the regulated GMO field to forage will stop over in the nonregulated border on the way out of the field for additional foraging, leaving the pollen from the GMO field there. The pollen trap works as a way for pollinators to “wipe their feet” before they leave the regulated field trial area.

In crops where flowering occurs once in the season for a predicable period of time — like corn — it is possible to minimize pollen flow to compatible recipients using temporal isolation. This means planting the regulated GMO field trial at a prescribed period of time before or after other, potentially compatible crops in the area are planted. When the regulated GMO corn trial produces pollen, all the nonregulated corn in the area either has already completed flowering or will not flower for some time; therefore, there are no female flowers outside of the field trial area for the pollen to fertilizer.

Another strategy for minimizing pollen flow is using physical barriers to prevent pollinators from getting to the flowers and the pollen. Depending on the architecture of the plant, different strategies can be used. This could include: 1) bags over individual flowers on each plant, 2) fine mesh bags over the entire plant that are effective at blocking insect pollinators but still allow for photosynthesis or 3) tenting, such as high tunnels, over entire plots or trials.

A very straightforward strategy to minimize pollen movement is removing flowers before they shed pollen or ending the field trial before flowering occurs. The purpose of some field trials of regulated GMO crops may be to evaluate the phenotype of the plant at early growth stages. Where this is the case, flowers can be removed from the plant (for example, by removing tassels from the top of a corn plant, which is where the pollen is made), or the entire field trial can be mowed down and tilled under before the flowers open.

In regard to the last part of your question (“How do you go about preventing nematodes and microorganisms from getting out of a controlled environment?”), movement of these organisms in or out of the regulated GMO trial is not a risk because they will not carry seed, pollen movement has been minimized, as described above, and there is no indication or evidence that these organisms will transfer the trait to plants outside of the field trial area. Therefore, for most regulated GM field trials there is neither a practical need nor a regulatory requirement to contain these organisms.

Caviness, C.E. 1966 Estimates of natural cross-pollination in Jackson soybeans in Arkansas. Crop Sci. 6:211.
OECD. 2008. OECD Seed Schemes “2008”, Annex VII to the Decision: OECD Scheme for the Varietal Certification of Crucifer Seed and Other Oil or Fibre Species Seed Moving in International Trade.
OECD Document C(2000)146/FINAL Incl. 2003, 2004, 2005, 2006 & 2007 Amendments. OECD, Paris. 45 pp.
Simpson, D.M., and E.N. Duncan. 1956. Cotton pollen dispersal by insects. Agronomy Journal 48:305-308.
Van Deynze, A.E., F.J. Sundstrom and K.J. Bradford. 2005. Pollen-mediated gene flow in California cotton depends on pollinator activity. Crop Science 45: 1565-1570.