October 13 - 15, 2004 Meeting Agenda

3. Please identify other crops that have no wild or weedy relatives in the United States with which they can produce viable hybrids in nature, e.g., papaya, peanut, and/or chickpea.
The Agency anticipates the need to evaluate data addressing whether transgenic plant species are capable of genetic exchange with wild or weedy plant relatives. In general, EPA is focused on the potential for genetic exchange that can occur in the field. However, evaluations of the potential for genetic exchange are likely to include laboratory studies that are not necessarily an accurate indicator of plants’ ability to exchange genetic material outside the lab.
4. What laboratory techniques used to achieve genetic exchange between species (e.g., embryo rescue, use of intermediate bridging crosses, protoplast fusion) are not indicative of possible genetic exchange between these species in the field? Conversely, what techniques, if any, used in laboratory or greenhouse experiments provide the most reliable indication of ability to hybridize in the field?

ISSUES ASSOCIATED WITH DEPLOYMENT OF A TYPE OF PLANT-INCORPORATED PROTECTANT (PIP), SPECIFICALLY THOSE BASED ON PLANT VIRAL COAT PROTEINS (PVCP-PIPS)

THURSDAY, OCTOBER 14, 2004
Holiday Inn - National Airport
2650 Jefferson Davis Highway
Arlington,VA 22202
Telephone: (703) 684-7200

• 8:30 AM Introduction and Identification of Panel Members – Stephen Roberts, Ph.D. (FIFRA SAP Session Chair)
• 8:35 AM Administrative procedures by Designated Federal Official - Mr. Paul Lewis
• 8:40 AM Follow-up from Previous Day’s Discussion – Melissa Kramer, Ph.D. (Office of Science Coordination and Policy, EPA)
• 9:00 AM Panel Discussion (continued)

  EPA recognizes that it may be possible to genetically engineer a plant such that concerns about gene flow to wild or weedy relatives are significantly reduced. However, according to the 2004 NRC report, Biological Confinement of Genetically Engineered Organisms, current techniques for bioconfinement (e.g., sterile triploids, male sterility) are imperfect and are not guaranteed to eliminate entirely gene flow to existing wild relatives. Recent modeling studies suggest imperfections in bioconfinement could result in significant levels of gene introgression in compatible plant relatives over a period of decades.
  
  5. Given that current bioconfinement techniques are not 100% effective, what would the environmental implications be of extremely low transfer rates of virus-resistance genes over time?

  EPA recognizes that concerns about gene flow to wild or weedy relatives may be ameliorated if the introduced virus-resistance trait would give little or no selective advantage to the recipient plant, as would occur if the plant were already tolerant or resistant to the virus to which resistance is conferred. It is obvious that such resistance does exist in some populations because traditional breeding for resistance relies on finding a source of resistance within related cultivated species, old varieties, or wild species.
  
  6. Please comment on the prevalence of tolerance and/or resistance to viruses in wild relatives of crops.

• 10:00 AM BREAK
• 10:15 AM Panel Discussion (continued)

7. Please specify techniques that do or do not provide measures of tolerance and/or resistance that are relevant to field conditions.
8. How do environmental or other factors (e.g., temporal variations) affect tolerance and/or resistance? Given the expected variability, what measures of tolerance and/or resistance would be reliable?
9. What would be the ecological significance if a plant population acquired a small increase in viral tolerance and/or resistance above a naturally-occurring level?

Based on the hypothesis that concerns about the consequences of gene flow to a wild or weedy relative in the United States may be negligible in certain cases, the Agency is considering whether there are mechanisms to adequately address concerns associated with gene flow so that certain types of VCPs would be of such low risk that they would not need to be regulated by EPA. Below are examples of three conditions (modified from those proposed in 1994) that are intended to significantly reduce any potential adverse effects of gene flow with plants containing a PVCP-PIP.

(1) The plant into which the PVCP-PIP has been inserted has no wild or weedy relatives in the United States with which it can produce viable hybrids in nature, e.g., corn, tomato, potato, or soybean; or

(2) Genetic exchange between the plant into which the PVCP-PIP has been inserted and any existing wild or weedy relatives is substantially reduced by modifying the plant with a scientifically documented method (e.g., through male sterility); or

(3) It has been empirically demonstrated that all existing wild or weedy relatives in the United States with which the plant can produce a viable hybrid are tolerant or resistant to the virus from which the coat protein is derived.

10. Please comment on how necessary and/or sufficient these conditions are to minimize the potential for the PVCP-PIP to harm the environment through gene flow from the plant containing the PVCP-PIP to wild or weedy relatives. Would any other conditions work as well or better?

Viral Interactions
Interactions between introduced plant virus sequences and other invading viruses in transgenic plants (e.g., during recombination or heterologous encapsidation) may be a concern to the extent that such events may increase in frequency or be unlike those expected to occur in nature. It has been hypothesized that such events could lead to the creation of viruses with new disease states or transmission properties. The Agency is evaluating the circumstances that might increase the potential for such events to occur and the potential environmental consequences of novel viral interactions in light of the 2000 NRC report which stated that, “[m]ost virus-derived resistance genes are unlikely to present unusual or unmanageable problems that differ from those associated with traditional breeding for virus resistance.” The report went on to suggest that risks might be managed by particular ways of engineering transgenes. However, under either of the 1994 proposed exemptions, the Agency would be unable to ensure that such strategies were implemented. The Agency’s literature review, “Viral interactions in viral coat protein transgenic plants,” discusses possible ways of managing these potential risks in detail.
Viral interactions may occur in natural, mixed infections which are common in plants. Hypothetical concerns related to potential adverse effects resulting from viral interactions between infecting viruses and PVCP-PIPs in transgenic plants may be attributed to opportunities for interactions not expected to occur in nature. EPA is interested in evaluating the significance of novel viral interactions involving a viral transgene.
11. To what extent are novel viral interactions (e.g., recombination, heterologous encapsidation) involving a viral transgene an environmental concern?
Mixed viral infections can be extremely common in crops and other plants. However, scientific uncertainty exists as to whether recombination and heterologous encapsidation would occur more or less frequently in the case of a viral transgene and an infecting virus interaction as compared to such interactions in mixed infections of a transgenic plant’s non-bioengineered counterpart.
12. What conclusions can be drawn as to whether the likelihood of recombination and/or heterologous encapsidation would be increased or decreased in a transgenic plant compared to its non-bioengineered counterpart?

A number of methods for reducing the frequency of recombination and heterologous encapsidation have been identified. While the effectiveness of these techniques has been verified for particular cases, their applicability to all PVCP-PIPs is unclear. Recognizing that it would be difficult for a product developer to measure rates of recombination, heterologous encapsidation, or vector transmission under field conditions, EPA is considering whether it would be necessary to verify that such methods worked in any particular instance by measuring rates in modified versus unmodified plants.
13. How effective is deleting the 3’ untranslated region of the PVCP gene as a method for reducing the frequency of recombination in the region of the PVCP gene? Is this method universally applicable to all potential PVCP-PIP constructs? Would any other methods work as well or better? Which methods are sufficiently effective and reproducible such that actual measurement of rates to verify rate reduction would be unnecessary?
14. Are any methods for inhibiting heterologous encapsidation or transmission by insect vectors universally applicable to all PVCP-PIPs? Which methods are sufficiently effective and reproducible such that actual measurement of rates to verify rate reduction would be unnecessary?
15. How technically feasible would it be to measure rates of recombination, heterologous encapsidation, and vector transmission in PVCP-PIP transgenic plants in order to show that rates are reduced?

ISSUES ASSOCIATED WITH DEPLOYMENT OF A TYPE OF PLANT-INCORPORATED PROTECTANT (PIP), SPECIFICALLY THOSE BASED ON PLANT VIRAL COAT PROTEINS (PVCP-PIPS)

FRIDAY, OCTOBER 15, 2004
Holiday Inn - National Airport
2650 Jefferson Davis Highway
Arlington,VA 22202
Telephone: (703) 684-7200

• 8:30 AM Introduction and Identification of Panel Members – Stephen Roberts, Ph.D. (FIFRA SAP Session Chair)
  
• 8:35 AM Administrative procedures by Designated Federal Official - Mr. Paul Lewis
  
• 8:40 AM Follow-up from Previous Day’s Discussion – Melissa Kramer, Ph.D. (Office of Science Coordination and Policy, EPA)
  
• 9:00 AM Panel Discussion (continued)

  EPA recognizes that scientific disagreement exists as to the likelihood of environmental impacts due to novel viral interactions in transgenic plants modified with PVCP-PIPs. The Agency is considering whether there are available mechanisms to adequately address concerns associated with novel viral interactions so that certain types of PVCP-PIPs would be of such low risk that they would not need to be regulated by EPA. Below are examples of conditions that might significantly reduce either the novelty [(1) and (2)] or frequency [(3) and (4)] of viral interactions in PVCP-PIP transgenic plants.
  
  (1) The genetic material of the PVCP-PIP is translated and/or transcribed in the same cells, tissues, and developmental stages naturally infected by every virus from which any segment of a coat protein gene used in the PVCP-PIP was derived.
  
  (2) The genetic material of the PVCP-PIP contains coat protein genes or segments of coat protein genes from viruses established throughout the regions where the crop is planted in the United States and that naturally infect the crop into which the genes have been inserted.
  
  (3) The PVCP-PIP has been modified by a method scientifically documented to minimize recombination, (e.g., deletion of the 3’ untranslated region of the coat protein gene).
  
  (4) The PVCP-PIP has been modified by a method scientifically documented to minimize heterologous encapsidation or vector transmission, or there is minimal potential for heterologous encapsidation because no protein from the introduced PVCP-PIP is produced in the transgenic plant or this virus does not participate in heterologous encapsidation in nature.
  
  16. Please comment on how necessary and/or sufficient each of these conditions is to minimize the potential for novel viral interactions. Please address specifically what combination would be most effective or what conditions could be modified, added, or deleted to ensure that potential consequences of novel viral interactions in PVCP-PIP transgenic plants are minimized.
  

• 10:00 AM BREAK
• 10:15 AM Panel Discussion (continued)

Modifications of the construct may also potentially create the opportunity for novel viral interactions because the inserted virus sequences could be unlike any that occur naturally.

19. To what degree and in what ways might a PVCP gene be modified (e.g., through truncations, deletions, insertions, or point mutations) before it would be a concern that novel viral interactions due to the modifications could occur because the PVCP gene would be significantly different from any existing in nature?
The potential risk issues identified in this paper are specific to virus-resistant transgenic plants. However, the Agency recognizes that it may be necessary to evaluate other information related to the PVCP-PIP.

20. Would any additional requirements related to PVCP-PIP identity and composition (e.g., demonstration that the transgene has been stably inserted) be needed for significant reduction of risks associated with PVCP-PIPs?

21. Are there any considerations beyond gene flow, recombination, and heterologous encapsidation as posed in the preceding questions that the Agency should consider in evaluating the risk potential of PVCP-PIPs (e.g., synergy)?

Please be advised that agenda times are approximate. For further information, please contact the Designated Federal Official for this meeting, Mr. Paul Lewis, via telephone: (202) 564-8450; fax: (202) 564-8382; or email: lewis.paul@epa.gov