Confinement

Confinement, or measures to keep experimental organisms within a zone having designated borders or limits, is the most common method for preventing or minimizing the unintentional spread of a GMO or its genetic material.

Physical strategies for confinement

Physical means to confine GM plants and plant parts include geographical or spatial isolation or use of structures such as fences, screens, mesh, and the like to keep animals out and prevent "unauthorized harvest." In order to be considered an environmental risk, transgenic pollen must be able to fertilize plants of a sexually compatible

Crop

Foundation

Registered

Certi

Corn (inbred)a

200

-

Corn (hybrid)

-

200

Cotton (hybrid) b

0

0

0

Millet (selfed)c

400

400

200

Millet (crossed)d

0

0

0

Mung beans d

0

0

0

Onion

1,600

800

400

Peanuts d

0

0

0

Pepper

200

100

30

Potato (male fertile)

400

400

400

Potato (male sterile)

0

0

0

Rapeseed (selfed)

400

100

Rapeseed (crossed)

200

100

Rice

3

3

3

Sorghum (hybrid)

300

300

200

Sorghum (hybrid)

-

200

Soybeansd

0

0

0

Sunflower6

800

800

800

Tomato

200

100

10

Watermelon'

800

800

400

SOURCE: Modified from "Genetic and Crop Standards" of the AOSCA:

http://www.aosca.org/

a. No isolation is required for the production of hand-pollinated seed.

b. Isolation distance between upland and Egyptian types must be at least 400, 400, and 200 meters for Foundation, Registered, and Certified classes, respectively.

c. Distance adequate to prevent mechanical mixture is necessary.

d. Isolation between millets of different genera must be 2 meters.

e. An isolation distance of 1,600 meters is required between oil and nonoil sunflower types and between either type and other volunteers or wild types.

f. The minimum distance may be reduced by 50 percent if natural or artificial barriers adequately protect the field.

SOURCE: Modified from "Genetic and Crop Standards" of the AOSCA:

http://www.aosca.org/

a. No isolation is required for the production of hand-pollinated seed.

b. Isolation distance between upland and Egyptian types must be at least 400, 400, and 200 meters for Foundation, Registered, and Certified classes, respectively.

c. Distance adequate to prevent mechanical mixture is necessary.

d. Isolation between millets of different genera must be 2 meters.

e. An isolation distance of 1,600 meters is required between oil and nonoil sunflower types and between either type and other volunteers or wild types.

f. The minimum distance may be reduced by 50 percent if natural or artificial barriers adequately protect the field.

tion of Official Seed Certifying Agencies (AOSCA9), describes the isolation distances required to avoid genetic contamination by pollen dispersal in the production of certified seed. (The terms foundation, registered, and certified refer to classes of certified seed produced and handled under procedures established by the certifying agency according to each class for maintaining genetic purity and identity. In simple terms, they are the first-, second-, and third-generation progeny of breeder seed, respectively.) The accompanying table shows isolation distances for the three certified seed classes of selected crops.

Where available land is insufficient for spatial isolation, one or more of the following procedures can reduce or prevent GMO or transgene spread via pollen or seed:

• Plant border rows of the non-GM variety around the test plot to "trap" pollen from the GMO.

• Bag flowering structures to screen out pollinating insects and/or prevent pollen spread by insect vectors, wind, or mechanical transfer.

• Cover female flowers after pollination to prevent loss or dissemination of GM seed.

• In cases where research objectives do not require seed production for analysis or subsequent planting, remove flower heads before pollen and seed production.

• Harvest plant material of experimental interest before sexual maturity.

• Locate test plots surrounded by roads or buildings.

species growing in the vicinity. Crop breeders are an excellent source of information about the presence and distribution of cross-fertile wild or weedy relatives of cultivated species. Genetic and Crop Standards, an annual publication of the Associa-

Biological strategies for confinement

Biological processes can provide highly effective means of preventing unintended transmission of genetic material. Reproductive isolation, a common method of biological confinement, can be achieved in a variety of ways:

• Grow GM plants in an area where sexually compatible wild or weedy species are not found.

• Remove all plants of sexually compatible wild or weedy species found within the known effective pollinating distance of the GM crop.

• Cover or bag flowers to screen out insect pollinators or prevent wind pollination.

• Prevent production of viable pollen by using genetic male sterility, applying a gametocyte, or removing all reproductive structures at an early stage of development.

• Recover tubers, rhizomes, storage roots, and all tissues capable of developing into mature plants under natural conditions.

• Exploit differences in flowering time so that GM pollen is not shed at the time when sexually compatible plants nearby are receptive.

• Engineer genes into chloroplast DNA instead of chromosomal DNA, since pollen from most species does not contain chloroplasts. This technology is still in its infancy, may not be effective for all genes, and would not be effective in plants in which chloroplasts are transferred by pollen.

• Engineer transgenic plants to produce sterile seed. This technology was developed as a "technology protection" system to secure intellectual property rights for the improved seed (the so-called Terminator gene). It is highly effective for risk- management purposes, but has raised ethical questions regarding seed saving and the role of multinational corporations in controlling seed and therefore food supplies in developing countries.

Other strategies for confinement

For small-scale field tests, environmental conditions can be manipulated to limit reproduction, survival, or dissemination of GMOs outside the experimental area. For example, temperature, water supply, humidity, and photoperiod can be controlled naturally by suitable placement of the test site, or artificially by using irrigation, lights, misters, and the like. In some parts of the world, trials can be conducted in which climatic conditions preclude flowering or survival outside the experimental area.

Chemicals can be used to limit survival and reproduction of GMOs outside the trial area. Herbicides, fungicides, insecticides, disinfectants, or other materials toxic to the test organism can be applied, but effects of the chemical on other organisms or the immediate vicinity must be taken into account. At the end of an experiment, the whole experimental area, if necessary, can be treated chemically or sterilized. Lastly, decreasing the number of test organisms or the land area used in an experiment may reduce the possibility of unintended dissemination.

In sum, organisms that engender little or no risk to the environment may require no or minimal confinement. GMOs with a very high potential for causing serious adverse effects in some cases may not be safely grown outside of containment. Most agricultural GMOs will be found safe for small-scale (field-test) release when specific risk-management procedures are part of the experimental design.

Other Standard Risk-Management Procedures

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