Risk Assessment and Risk Management Plan

Section 7 Evaluation of Pleiotropic Effects of Genetic Modification

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Section 7 Evaluation of Pleiotropic Effects of Genetic Modification

  1. A single plant gene can have an influence on multiple, sometimes unrelated, plant traits. This phenomenon is known as pleiotropy. Single genes inserted into a plant by genetic modification can also be pleiotropic and it is necessary to evaluate genetically modified plants for unintended, pleiotropic effects of the inserted genes, such as changes in agronomic characteristics.

  2. The applicant has indicated that because both of the ACC synthase genes targeted for down-regulation are only induced within fruit during the ripening process, and the etr1-1 gene is controlled by a fruit specific promoter, it is not expected that any other processes will be adversely affected in the transgenic plants.

  3. However, there is a potential for down-regulation of ethylene production to have other, pleiotropic effects on the plant. For example, down-regulation of ethylene production in the fruit could result in changes in the response of the fruit to pathogenic or non-pathogenic microorganisms. Down-regulation of ethylene production may also occur in non-fruit tissues of the plant, and there is a potential for effects on plant growth and development and responses to pathogenic and non-pathogenic microorganisms.

  4. As a condition of licence, the applicant is required to monitor the GM papayas for any unusual responses to pathogenic or non-pathogenic microorganisms, such as increased or decreased disease occurrence or severity in comparison to what is normally associated with cultivation of non-GM papayas.

  5. Evaluation of other characteristics of the GM papaya plants that may be affected by pleiotropy, including overall agronomic performance and compositional analysis of the fruit, is not proposed for this release. Future applications to release these GM papayas would require information regarding potential pleiotropic effects on agronomic performance and fruit composition.

  6. Food Standards Australia New Zealand (FSANZ), is responsible for human food safety assessment. Although the applicant has not applied to FSANZ for evaluation of material from the GM papayas for use in human food, FSANZ approval would need to be obtained before GM papayas could be used as human food.

APPENDIX 2 Toxicity and allergenicity to HUMANs and other organisms

  1. Under section 51 of the Act, the Regulator is required to consider risks to human health and safety and the environment in preparing the risk assessment and the risk management plan. This part of the document considers the potential toxicity and allergenicity of the GMOs or their novel proteins for humans and for other organisms as a consequence of the proposed dealings.

Section 1 Nature of the potential toxicityand allergenicity hazard

  1. Toxicity is the cascade of reactions resulting from exposure to a dose of chemical sufficient to cause direct cellular or tissue injury or otherwise inhibit normal physiological processes (Felsot 2000). Allergic responses are immune system reactions, resulting from stimulation of a specific group of antibodies known as IgE, or sensitisation of specific tissue bound lymphocytes (Taylor & Lehrer 1996; FAO/WHO 2000). Allergy has a well defined etiology (ie. biochemical cause) that is quite different from toxicity.

  2. The potential for the GM papayas to be toxic or allergenic to humans or to be toxic to other organisms due to either expression of the novel gene products, decreased expression of the targeted naturally occurring genes or because of unforeseen, unintended effects of the genetic modification is considered. The nature of these hazards depends on the intrinsic characteristics of non-GM papaya (see The Biology and Ecology of Papaya (paw paw), Carica papaya L., in Australia, available at the OGTR website [http://www.ogtr.gov.au]), the extent to which these may be modified by the inserted genes or genetic constructs (see Appendix 1), the potential exposure of people or other organisms to the GM papayas or their by-products and on other sources of exposure to the introduced proteins.

  3. If the GM papayas in the proposed release were to be toxic or allergenic to humans or toxic to other organisms, potential hazards could include adverse impacts on:

  4. Human workers associated with the release;

  • mammals and wildlife, including bats, rodents and possums that may feed on papaya fruit;

  • invertebrates, including both beneficial insects (pollinators, parasitoids or predators of insect pests) and arthropod pests; and

  • communities of microorganisms, particularly soil microorganisms.

Section 1.1 Exposure of people to GM papaya

  1. Humans associated with the proposed release will be in contact with papaya plants and papaya fruit. Potentially, harm could occur if the GM papayas became toxic or allergenic than non-GM papaya to people via occupational exposure.

  2. It should be noted that there will be no opportunity for humans to consume fruit or other products of the GM papayas proposed for release. However, potential toxicity and allergenicity hazards associated with consumption of GM papaya fruit with delayed fruit ripening characteristics are considered in this Appendix in view of potential future applications (which would be subject to separate applications and assessments) for larger scale release of GM papaya varieties resulting from the release currently proposed.

  3. There have been no reported adverse toxic or allergenic effects on human health through occupational exposure resulting from the GM papaya plants released under PR-128.

Section 1.2 Exposure of other organisms to GM papaya

  1. The GM papaya plants in the proposed dealing will be grown inside an insect-proof netting enclosure (a knitted 2.0 mm2 nylon grid net) that will exclude many insects and other arthropods, and all birds and mammalian herbivores and fruit eaters such as rodents, bats and possums. The potential for exposure of these organisms to the GM papaya plants and fruit is thus low. However, potential toxicity hazards to these organisms associated with GM papaya with delayed fruit ripening are considered in light of potential future applications for larger scale releases.

  2. Exposure of soil microorganisms to the GM papaya plants will be limited due to the limited scale of the proposed release. Again, potential toxicity hazards to these organisms are considered in light of potential future applications for larger scale releases.

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