As part of the evaluation process for this licence application, a risk management plan has been developed to addresses the risks identified (refer to Conclusion of the risk assessment, above). This plan is given effect by the licence conditions imposed. The key licence conditions are outlined below.
Toxicity or allergenicity to humans and other organisms
Licence conditions have been imposed to:
restrict access to the site to authorised personnel;
fully enclose the GM papaya plants in a self-supporting insect-proof enclosure that is secured at ground level (this condition has been imposed largely to manage the risks of weediness and gene flow (see below) but also limits the potential for realisation of any risk of toxicity or allergenicity);
provide appropriate signage at the release site to indicate that GM papayas are being grown within the enclosure and that plants or other material (eg. fruit) must not be removed, except for laboratory analysis as expressly authorised by the licence;
prohibit the use of the GM papayas and any of their by-products for human or animal food; and
establish a system for accounting for all fruit produced by the GM papayas and record instances of damage or removal of such fruit.
Licence conditions have been imposed to:
enclose the release site within a self-supporting insect-proof enclosure (which also excludes flying foxes or other animals which may otherwise disperse seed); and
Licence conditions have been imposed which require the applicant to:
enclose the release site within a self-supporting insect-proof enclosure (which excludes key pollinators);
remove all male flowers before they open, to prevent dispersal of pollen;
immediately remove and destroy all flowers and fruits to prevent dispersal of pollen (or seeds), in the event that the insect-proof enclosure is damaged and cannot be repaired immediately; and
install insect-light traps capable of attracting and trapping key potential pollinators within the enclosure, to monitor the efficacy with which the insect-proof netting excludes such insects.
General licence conditions
Any licence issued by the Regulator also contains a number of general conditions, which are also relevant to risk management. These include, for example:
identification of the persons or classes of person covered by the licence;
a requirement that the applicant allow access to the release sites by the Regulator, or persons authorised by the Regulator, for the purposes of monitoring or auditing; and
a requirement to inform the Regulator if the applicant becomes aware of any additional information about risks to human health or safety or to the environment.
Monitoring and enforcement of compliance by the OGTR
As well as the legislative capacity to enforce compliance with licence conditions, the Regulator has additional options for risk management. The Regulator can direct a licence holder to take any steps the Regulator deems necessary to protect the health and safety of people or the environment. The OGTR also independently monitors releases that it has authorised. At least 20% of all release sites will be inspected each year, in accordance with a monitoring and compliance strategy based on risk profiling, to determine whether licence holders are complying with the licence conditions, or whether there are any unforseen problems.
Detailed information on the evaluation of the application, including the licence conditions, is available in the risk assessment and risk management plan document for this application, which can be obtained from the web site of the Office of the Gene Technology Regulator (www.ogtr.gov.au), or by calling 1800 181 030 (please quote application number DIR 026/2002).
chapter 1 BACKGROUND
This chapter provides information about the background to the application and previous releases of relevant GMOs into the environment.
Section 1 The application
Field trial for evaluation of GM papaya to delay fruit ripening and test the expression of the introduced genes
University of Queensland
Brisbane QLD 4072
Common name of the parent organism:
Papaya or pawpaw
Identity of the gene(s) responsible for the modified trait(s):
capacs 1 and capacs 2 genes from papaya (genes associated with ethylene production and fruit ripening)
etr1-1 gene from Arabidopsis thaliana (ethylene perception and fruit ripening)
-glucuronidase gene (uidA) from Escherichia coli (reporter gene)
nptII gene from bacterial Tn5 transposon (antibiotic resistance gene)
Proposed Release Date:
June 2003 – December 2006. Continued evaluation of 20 GM papayas planted since 2002 and release of up to 300 new papaya plants in August 2003.
The OGTR has received an application (licence application number DIR 026) from the University of Queensland (UQ) for the intentional release of genetically modified (GM) papayas into the environment in the shire of Redlands Queensland (Qld). Approval would enable the continued evaluation of three types of GM papayas planted since 2002. The release was authorised by the previous voluntary system and under ‘deemed’ licence PR-128, which expires in June 2003 under the transitional arrangements of Section 190 of the Gene Technology Act 2000 (the Act). The applicant also proposes the release of five new types of GM papaya plants, in August 2003. Up to 300 GM papaya plants will be grown on a single site covering one hectare for a three year period.
The proposed release aims to evaluate modified fruit ripening characteristics of eight different GM papayas. However, fruit production is not possible in glasshouse-grown papaya trees, which can grow to several metres in height before reproductive maturity. Accordingly, the applicant seeks a licence to release the GM papaya plants into the field under limited and controlled conditions to evaluate fruit ripening characteristics.
Section 1.1 The proposed dealings
The UQ seeks approval to grow six different types of GM papayas that have been genetically modified to delay fruit ripening by decreasing the natural production (‘down-regulating’) ACC (1-amino-cyclopropane-1-carboxylic acid) synthase, an intermediate enzyme in the biosynthesis of the plant hormone, ethylene (see Table 1, Appendix 1). In addition, UQ proposes to grow one type of GM papaya that has been modified to delay fruit ripening by a change in the perception of ethylene. Another type of GM papaya has also been modified to express a reporter gene that will allow evaluation of the effectiveness of the promoter controlling expression of the introduced genes.
The proposed limited and controlled trial involves planting up to 300 glasshouse-grown GM papaya plants into the field at one site in the Shire of Redlands, Qld. The GM papaya plants will be planted inside an insect-proof netting enclosure*.
Papaya fruit has poor storage qualities. If fruit ripening is delayed over several days to weeks it may be possible to decrease spoilage due to over-ripening during transportation and storage. The applicant proposes to grow the GM papayas under insect-proof netting in the field for fruit production, to monitor the rate of fruit ripening. In this regard, a majority of fruit will be harvested before they are fully ripe, but for a limited number of fruit, the rate of ripening will be assessed on the tree. It is anticipated that key information regarding the genetic modifications and physiological, nutritional and quality attributes of the fruit will be obtained. The expression levels of the naturally occurring and introduced ACC synthase genes and the introduced ethylene perception gene will also be determined. Reporter gene expression will also be evaluated to assess the effectiveness of the regulatory sequence (promoter) that controls the expression of the introduced ACC synthase genes.
None of the fruit produced from these trials is intended for human or animal consumption.
Section 1.2 Parent organism
The parent organism is Carica papaya L. (papaya, or paw paw), which is exotic to Australia, but is grown both commercially and in domestic gardens in tropical and sub-tropical parts of Australia from Western Australia to New South Wales.
C. papaya is not a pathogenic organism and the genetic modifications of the papaya plants proposed for release will not alter this. More detailed information on papaya can be found in a review document ‘The Biology and Ecology of Papaya (paw paw), Carica papaya L., in Australia’ that was produced in order to inform this risk assessment process. This document is available at the OGTR website (http://www.ogtr.gov.au).
Section 1.3 Genetic modification and its effect
Six types of GM papayas that have been genetically modified to delay fruit ripening which contain additional copies of genes encoding the enzyme ACC synthase (both sense and antisense versions of the capacs 1 or capacs 2 genes from Carica papaya). These additional copies initiate down-regulation of naturally occurring ACC synthase gene activity through two different methods. Together, these methods are known as ‘gene silencing’, as they prevent a target plant gene producing the protein that it normally makes, thus ‘silencing’ the activity of the gene.
The ACC synthase genes are associated with biosynthesis of ethylene. It is expected that production of ethylene will be decreased due to inhibition of production of ACC, a metabolic intermediate required for the natural synthesis of ethylene in plants. One response to decreased ethylene production is to reduce the rate at which fruit ripen.
One type of GM papaya will test a different approach for delaying fruit ripening. It has been genetically modified to contain the etr1-1 gene, encoding a modified ethylene receptor protein from Arabidopsis thaliana. The etr1-1 gene encodes a non-functional version of the ethylene receptor gene etr1. In GM papaya plants containing the etr1-1 gene, the fruits are expected to be partially insensitive to ethylene, and thereby, delay ripening.
Some plants proposed for release express the uidA gene from the bacterium, Escherichia coli. This gene codes for the enzyme -glucuronidase (GUS). The GUS enzyme converts a colourless substrate into a blue colour in a simple laboratory assay and is used as a reporter or ‘marker’ to detect tissues that have been successfully genetically modified. Exposure of plant tissues containing the GUS gene to this substrate facilitates measurement of the expression of the uidA gene. The applicant proposes to release some papaya plants that have been modified by inserting the uidA gene, instead of the fruit ripening genes, as a means of confirming the effectiveness of the promoter that is used to control the expression of the ACC synthase genes. GUS activity will also be used to indicate the plant tissue(s) in which the genes are expressed.
The plants also contain bacterial genes conferring resistance to the antibiotics kanamycin and neomycin (nptII gene) and ampicillin (bla gene). These genes were used to select bacteria and plants containing the desired fruit ripening and GUS genes, in the laboratory. The bla gene is under the control of a bacterial promoter and therefore it will not be expressed in the GM papayas.
Short regulatory sequences that are required to control the functioning of the genes are also present in the GM papayas. These are derived from the cauliflower mosaic virus, Agrobacterium tumefaciens (a common soil bacterium) and apple (Malus domesticus). Although the first two of these organisms are plant pathogens, the regulatory sequences comprise only a small part of their total genome and are not, in themselves, capable of causing disease.
Further details about the genetic modification process and the introduced genes are provided in Appendix 1, Sections 3 and 4.
Section 1.4 Method of gene transfer
Each of the genes and their associated regulatory sequences were introduced into papaya by microprojectile bombardment. This technique involves coating the DNA containing the genes onto very small tungsten or gold particles which are ‘shot’ into the papaya tissue. Particle bombardment has been widely used in Australia and overseas for introducing new genes into plants.