264. The following factors are taken into account when postulating relevant risk scenarios:
- the proposed dealings, which may be to conduct experiments, develop, produce, breed, propagate, grow, import, transport or dispose of the GMOs, use the GMOs in the course of manufacture of a thing that is not the GMO, and the possession, supply and use of the GMOs in the course of any of these dealings.
- the proposed limits, if any
- the proposed controls, if any
- characteristics of the parent organism(s)
- routes of exposure to the GMOs, the introduced gene(s) and gene product(s)
- potential effects of the introduced gene(s) and gene product(s) expressed in the GMOs
- potential exposure to the introduced gene(s) and gene product(s) from other sources in the environment
- the environment at the site(s) of release
- agronomic management practices for the GMOs.
265. Five risk scenarios were identified and evaluated in the context of the large scale of the release proposed by the applicant and in the absence of proposed limits and controls. These are summarised in Table 13, where circumstances that share a number of common features are grouped together in broader risk categories. None of the risk scenarios were identified as a risk that could be greater than negligible. Therefore, they did not warrant further detailed assessment. More detail of the evaluation of these scenarios is provided later in this Section.
266. Some of the hybrid GM canolas proposed for release contain the antibiotic resistance marker gene nptII. The nptII gene and its product has already been considered in detail in previous RARMPs, including for DIR 021/2002 and also for the commercial release of cotton (see DIR 12/2002, DIR 022/2002, DIR 023/2002, and DIR 059/2005), and by other regulators (for example EFSA 2007). Since nptII has been found to pose no risks to either people or the environment, its potential effects will not be further assessed for this application.
267. As the GMOs are derived by conventional crossing, the risks from unintended changes to the biochemistry (including innate toxic or allergenic compounds), physiology or ecology of the GMOs are not expected to be greater than the parental GMOs, which were assessed as negligible (see DIR 020/2002 and DIR 021/2002). There is no evidence or reasonable expectation that interactive or additive effects are likely to occur in the hybrid canolas proposed for release as all of the proteins encoded by the introduced genes operate through independent biochemical pathways. Therefore, unintended changes will not be further assessed for this application.
268. All of the introduced regulatory sequences are derived from common plants, bacteria and viruses. Similar regulatory elements are naturally present in canola, and the introduced elements operate in same way as endogenous ones. Although the transfer of introduced regulatory sequences into new genetic contexts, either in other plants or other organisms, could result in unpredictable effects, the likelihood and impact of transfer of the introduced regulatory elements will not be different to those from endogenous regulatory elements. Hence these potential effects will not be further assessed for this application.
Table 13 Summary of risk scenarios from dealings with canola genetically modified for herbicide tolerance and a hybrid breeding system (InVigor® x Roundup Ready® canola)
| Risk category | Risk scenario | Identified risk? | Reason | |
|---|---|---|---|---|
| Pathway that may give rise to harm | Potential harm | |||
| Section 2.1 Production of a toxic or allergenic substance |
1. Exposure to GM plant material containing the proteins encoded by the introduced genes. | Allergic reactions in people or toxicity in people and other organisms | No |
|
| Section 2.2 The potential for spread and persistence of the GM canola plants in the environment |
1. Expression of the introduced genes for herbicide tolerance and a hybrid breeding system increasing the invasiveness of the GM canola. | Weediness; allergic reactions in people or toxicity in people and other organisms | No |
|
| Section 2.3 Vertical transfer of genes to sexually compatible plants | 3. Expression of the introduced genes in other canola plants | Weediness; allergic reactions in people or toxicity in people and other organisms | No |
|
| 4. Expression of the introduced genes in other sexually compatible plants | Weediness; allergic reactions in people or toxicity in people and other organisms | No |
|
|
| Section 2.4 Horizontal transfer of genes or genetic elements to sexually incompatible organisms |
5. Presence of the introduced genetic material in other organisms as a result of horizontal gene transfer | Weediness; allergic reactions in people or toxicity in people and other organisms | No |
|
2.1 Production of a toxic or allergenic substance
269. Toxicity is the adverse effect(s) of exposure to a dose of a substance as a result of direct cellular or tissue injury, or through the inhibition of normal physiological processes (Felsot 2000).Top of page
270. Allergenicity is the potential of a substance to elicit an immunological reaction following its ingestion, dermal contact or inhalation, which may lead to tissue inflammation and organ dysfunction (Arts et al. 2006).
271. A range of organisms may be exposed directly or indirectly to the proteins (and end products) encoded by the introduced genes for herbicide tolerance and a hybrid breeding system. Workers cultivating the GM canola would be exposed to all plant parts. FSANZ has approved the use of food derived from GM InVigor® canola and GM Roundup Ready® canola for human consumption (ANZFA 2000; ANZFA 2001b). These approvals also cover GM InVigor® x Roundup Ready® canola and therefore this is a potential source of exposure to people. Organisms may be exposed directly to the proteins through biotic interactions with GM canola plants (vertebrates, invertebrates, symbiotic microorganisms and/or pathogenic fungi), or through contact with root exudates or dead plant material (soil biota) or indirectly through the food chain.
Risk scenario 1. Exposure to GM plant material containing the proteins encoded by the introduced genes
272. Expression of the introduced genes for herbicide tolerance and a hybrid breeding system could potentially result in the production of novel toxic or allergenic compounds in the GM canola plants, or alter the expression of endogenous canola proteins. If humans or other organisms were exposed to the resulting compounds through ingestion, contact or inhalation of the GM plant materials, this may give rise to detrimental biochemical or physiological effects on the health of these people or other organisms.
273. The genes for herbicide tolerance and a hybrid breeding system introduced into the parental GM canola lines were all isolated from common soil bacteria, which are widespread and prevalent in the environment (see Chapter 1, Section 5.1.3). In addition, all of the parental GM canola lines are approved for commercial release (under DIR 020/2002 and DIR 021/2002), including for use in stockfeed. The CP4 EPSPS and PAT proteins are also present in GM cotton lines that have been approved for use in stockfeed since 2000 and 2006, respectively (see DIR 023/2002 and DIR 062/2005). Therefore, people and other organisms are already exposed to all of the proteins encoded by the introduced genes.
274. The toxicity of the parental GM canola lines was assessed in the RARMPs prepared for DIR 020/2002 and DIR 021/2002. This information was summarised and updated in Chapter 1, Section 5.4. The GM hybrid canolas proposed for release are not expected to be any more toxic or allergenic than the parental lines, as the same genes will be expressed under the control of the same regulatory elements. The novel proteins and their end products will be the same in the progeny of conventional breeding between the GM canola lines approved under licence DIR 021/2002 and Roundup Ready® canola as in the parental lines. Protein expression levels in InVigor® x Roundup Ready® canola are either similar to or lower than the low levels observed in the parental lines (see Chapter 1, Section 6.2.2). The proteins encoded by the introduced genes are well characterised and are not known to be toxic or allergenic (see Chapter 1, Section 5.1.3).
275. There is no evidence or reasonable expectation that interactive or additive effects are likely to occur in the hybrid canolas proposed for release or that they would result in new or increased risks relating to toxicity or allergenicity. The GOXv247 and CP4 EPSPS proteins present in Roundup Ready® canola operate through independent biochemical pathways unrelated to those of the BARNASE, BARSTAR or PAT proteins present in InVigor® canola. The goxv247 and cp4 epsps genes are not expected to interact with any of the genes present in InVigor® canola, their proteins or their metabolic pathways.
276. Analysis of the compositional data for canola seed from InVigor® x Roundup Ready® canola indicates that there are no meaningful differences in the levels of compounds, including natural toxicants, when compared to non-GM canola from the same hybrid background and to other commercial canola varieties. Overall, the agronomic characteristics of InVigor® x Roundup Ready® canola are comparable to their commercial MS8 x RF3 counterparts. These results indirectly support the lack of any interactive effects in hybrids resulting from conventional breeding between InVigor® canola lines and Roundup Ready® canola.
277. FSANZ has approved the use of food derived from GM InVigor® canola and GM Roundup Ready® canola for human consumption (ANZFA 2000; ANZFA 2001b). These approvals also cover GM InVigor® x Roundup Ready® canola.
278. Conclusion: The potential for allergic reactions in people, or toxicity in people and other organisms as a result of exposure to GM plant materials containing the proteins encoded by the introduced genes is not identified as a risk that could be greater than negligible. Therefore, it does not warrant further detailed assessment.
2.2 The potential for spread and persistence of the GM canola in the environment
279. This section addresses the question of whether or not the proposed dealings with the GMOs may lead to harm to human health and safety or the environment as a result of an increased potential for spread and/or persistence due to the genetic modification.280. All plants have the potential to lead to harm in certain environments. Harms that may arise from a certain plant species in a particular environment include:
- adverse effects on the health of people and/or animals
- reduction in the establishment, yield and/or quality of desired plants
- restriction in the physical movement of people, animals, vehicles, machinery and/or water
- adverse effects on environmental health, such as adverse changes to strata levels, nutrient levels, fire regime, soil salinity, soil stability, or by providing food and/or shelter to pests, pathogens and/or diseases.
282. Characteristics that influence the spread (dispersal of the plant or its genetic material) and persistence (establishment, survival and reproduction) of a plant species impact on the degree of its invasiveness. These characteristics include the ability to establish in competition with other plants, to tolerate standard weed management practices, to reproduce quickly, prolifically and asexually as well as sexually, and to be dispersed over long distances by natural and/or human means. The degree of invasiveness of a plant species in a particular environment gives an indication of the likelihood of its weediness in that environment. In addition to local experience, a history of weediness overseas can be used as an indicator for weediness in Australia.
283. Baseline information on the weediness of canola, including factors limiting the spread and persistence of non-GM canola plants, is given in The Biology of Brassica napus L. (canola) (OGTR 2011). In summary, canola is considered a major weed (naturalised and known to be a major problem at 4 or more locations within a State or Territory) in agricultural ecosystems in Australia (Groves et al. 2003). Surveys have shown that canola occurs as a volunteer weed in up to 10% of cereal crops in southern Australia (Lemerle et al. 1996). However, canola is not considered a significant weed nor invasive of natural undisturbed habitats in Australia (Dignam 2001; Groves et al. 2003). The weediness of the parental GM canola lines was assessed in the RARMPs prepared for DIR 020/2002 and DIR 021/2002. This information was summarised and updated in Chapter 1, Section 5.5.
284. Scenarios relating to altered spread and persistence of the GM canola, compared to non-GM canola, include expression of the introduced genes for herbicide tolerance and a hybrid breeding system increasing the invasiveness of the GM canola.
Risk scenario 2. Expression of the introduced genes for herbicide tolerance and a hybrid breeding system increasing the invasiveness of the GM canola
285. If the GM canola plants were to establish or persist in the environment, the exposure of humans and other organisms to the GM plant material could be increased. The potential for increased allergenicity in people or toxicity in people and other organisms as a result of contact with GM plant materials was discussed in Risk scenario 1 and was not considered an identified risk.
286. If the expression of the introduced genes for herbicide tolerance and a hybrid breeding system were to provide the GM canola plants with a significant selective advantage over commercially released canola plants and if they were able to establish and persist in non-cropped disturbed habitats and undisturbed natural habitats, this may give rise to lower abundance of desirable species, reduced species richness, or undesirable changes in species composition. Similarly, the GM canola plants could adversely affect cultivated areas if they exhibited a greater ability to establish and persist than commercially released canola.
287. As canola does not reproduce vegetatively under natural conditions, the most likely method of dispersal is via seed. Pod shattering can disperse seeds over short distances. It is also possible that GM canola plant material from windrows, including seed, could be blown beyond field boundaries. Dispersal distance would depend on the wind strength, the amount of trash on the ground and the moisture content of the material.
288. Dispersal of viable seed further from cultivated areas could occur in a variety of ways including endozoochory (dispersal through ingestion by animals), the activity of animals such as rodents and herbivores, through extremes of weather such as flooding or high winds, or via spillage during transport. If InVigor® x Roundup Ready® canola were commercialised, its distribution in unmanaged areas adjacent to fields and along transportation corridors would be expected to be comparable to that of non-GM volunteers.
289. The geographic range of non-GM canola in Australia is limited by a number of biotic and abiotic factors, including disease pressure, water and nutrient availability (OGTR 2011). As discussed in Chapter 1, Section 6.2.3, the agronomic characteristics of MS8 x RF3 x GT73 hybrids were comparable to their commercial MS8 x RF3 counterparts, apart from a small delay to maturity. Minimum and maximum values reported for MS8 x RF3 x GT73 plants were well within the range of values reported for the commercial hybrids. The production of the MS8 x RF3 x GT73 hybrids is not expected to alter the tolerance of plants to biotic or abiotic stresses that normally restrict geographic range and persistence of canola in natural habitats.
290. The weediness of the parental GM canola lines was assessed in the RARMPs prepared for DIR 020/2002 and DIR 021/2002. This information was summarised and updated in Chapter 1, Section 5.5. In summary, the introduced genes do not increase the potential weediness of the parental GM canola lines or provide these plants with an ecological advantage over non-GM canola, except in the presence of glyphosate (for Roundup Ready® canola) or glufosinate ammonium (for InVigor® canola). The GM hybrid canolas proposed for release are not expected to have any additional weediness traits, as the same genes will be expressed under the control of the same regulatory elements. Canola tolerant to glufosinate ammonium and glyphosate are no more competitive than the parent single herbicide tolerant plants (Simard et al. 2005).
291. All GM canolas proposed for release will contain two herbicide tolerance traits. Expression of these traits will confer a selective advantage over non-GM counterparts in environments in which the corresponding herbicide is applied, such as agricultural settings and along roadsides. As the mode of action of each gene is herbicide-specific, cross-tolerance to other herbicides is not expected in the GM lines. Glufosinate ammonium is not widely used in broad-acre cropping or management of disturbed areas, so control options for the InVigor® x Roundup Ready® canola in these areas will be similar to those currently available to control Roundup Ready® canola. The management of InVigor® x Roundup Ready® canola on roadsides and other disturbed habitats could be achieved by the variety of management strategies available, including a range of alternative herbicides, tank mixing, and non-chemical management methods such as mowing, slashing, cultivation, burning and grazing.
292. All herbicides sold in Australia are grouped by mode of action for the purpose of resistance management. The mode of action is indicated by a letter code on the product label, which is based on the resistance risk of each group of herbicides (CropLife Australia 2011). Glyphosate is a Group M herbicide and glufosinate ammonium is in Group N. Herbicides from different mode of action groups or products with multiple mode of action groups could be used to control InVigor® x Roundup Ready® volunteers. Specifically, herbicides from Groups B, C, F, G, H, I, L, O and Q are registered for use on canola in various crop and non-crop situations by the APVMA. In addition, several herbicides with multiple mode of action groups (eg Groups B + I, C + F, C + H, C + I, F + I, H + I, Q + L and K + B) are also registered for use on canola volunteers. Further details of registered herbicide products are available on the APVMA website.
293. The use of alternative herbicides for the control of InVigor® x Roundup Ready® canola volunteers may raise concerns that these herbicides could be more toxic or more persistent than glyphosate or glufosinate-ammonium. However, the APVMA registers herbicides on the basis that, when used as specified on the approved label, they will not compromise the health of users or the environment. The APVMA also has a program for reporting any adverse effects associated with agricultural chemical use and a program to review already registered agricultural chemicals.
294. When the weed risk potential of the GMOs is assessed based on the National Post-Border Weed Risk Management Protocol, they are considered to have no higher rating in terms of invasiveness or negative impacts than non-GM canola (see Chapter 1, Section 4.2) or the GM parental lines (see Chapter 1, Section 5.5).
295. Conclusion: The potential for improved survival of the GM canola through the expression of the introduced genes leading to increased spread and persistence in the environment is not identified as a risk that could be greater than negligible. Therefore, it does not warrant further detailed assessment.
2.3 Vertical transfer of genes to sexually compatible plants
296. Vertical gene flow is the transfer of genes from an individual organism to its progeny by conventional heredity mechanisms, both asexual and sexual. In flowering plants, pollen dispersal is the main mode of gene flow (reviewed in Waines & Hegde 2003). For GM plants, vertical gene flow could therefore occur via successful cross pollination between the plant and neighbouring plants, related weeds or native plants (Glover 2002).297. It should be noted that vertical gene flow per se is not considered an adverse outcome, but may be a link in a chain of events that may lead to an adverse outcome. For an increased potential for adverse effects to arise as a result of gene flow of the introduced genetic elements from the GM canola to sexually compatible plants, both of the following steps must occur:
- transfer of the introduced genetic elements to sexually compatible plants
- increased potential for adverse effects, such as toxicity or spread and persistence of the recipient plants, due to expression of the introduced gene.
299. InVigor® x Roundup Ready® canola was generated by conventional crossing of three genetic modification events and, as expected, the events have been inserted into different regions of the plant genome and therefore segregate independently of one another. This means, after any initial out-crossing of InVigor® x Roundup Ready® canola, any subsequent generations may contain the same genes as either InVigor® or Roundup Ready® canola. Transfer of these single events into sexually compatible species was considered prior to approval of licences for DIR020/2002 and 021/2002 and the risks were considered negligible.
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Risk scenario 3. Expression of the introduced genes in other canola plants
300. Transfer and expression of the introduced genes for herbicide tolerance and a hybrid breeding system to other canola plants could increase the weediness potential, or alter the potential allergenicity and/or toxicity of the resulting plants.
301. As discussed in Risk scenario 1, allergenicity to people and toxicity to people and other organisms are not expected to be changed in the hybrid GM canola plants by the combination of introduced genes. This will also be the case if the introduced genes are expressed in other canola plants.
302. As discussed in Risk scenario 2, the genes introduced into the hybrid GM canola plants are not expected to alter the tolerance of plants to biotic or abiotic stresses that normally restrict geographic range and persistence of canola in natural habitats. Similarly, they would not be expected to alter the geographic range or persistence of other canola plants if the introduced traits were transferred to their progeny.
303. However, the two herbicide tolerance genes present in the GM canola plants would confer a selective advantage in areas where the corresponding herbicides are applied. This would also be true if the traits were conferred to other canola plants in the environment.
304. In the broad-acre field situation, cross pollination between the hybrid GM canola proposed for release and other canola would be most likely to occur when canola crops are grown in adjacent paddocks and flower synchronously. Cross pollination may also occur where volunteer plants emerge after canola crops are harvested and develop to flowering stage, or where feral canola populations, resulting from seed being dispersed off-farm, establish along roadsides adjacent to cropping land where canola is planted.
Gene transfer to GM canola
305. Gene transfer could occur to other GM canola approved for either commercial or limited and controlled release. These include:
- Limited and controlled releases under DIRs 032/2002, 069/2006, 103, 104 and 105, or future limited and controlled release licences
- Commercial releases under DIR 020/2001 (Roundup Ready® canola) and DIR 021/2002 (InVigor® canola)
- Other GM canolas which may be approved for commercial release in the future.
306. Licence conditions for limited and controlled GM canola releases include measures to restrict gene flow. Additionally, controls placed on GM canola released under limited and controlled conditions include not using the GMOs in food or feed and destroying any GMOs and volunteer plants in the areas of the release in accordance with the licence. Therefore, the potential for any adverse outcome from gene transfer to these limited and controlled releases of GM canola as a result of the proposed dealings is considered negligible.
307. The only GM canolas currently approved for commercial release are the parent lines of the GMOs proposed for release. Outcrossing of InVigor® x Roundup Ready® to these commercially approved GM canola plants would result in plants highly similar to the GMOs proposed for release. Therefore, any adverse outcomes expected for those progeny would be comparable to InVigor® x Roundup Ready® canola.
308. Gene transfer could also occur to other GM canolas approved for commercial release in the future, which would lead to stacking of the genetic modifications. If any other canola was proposed for commercial release in the future, a risk assessment would be conducted taking into account potential stacking with already approved GM varieties. This would include consideration of potential interactions between different GM traits.
Gene transfer to non-GM, non-herbicide tolerant canola
309. Gene transfer to non-GM, non-herbicide tolerant canola plants would result in plants highly similar to the GMOs proposed for release or to their GM parents approved under DIR 020/2002 and 021/2002. Therefore, any adverse outcomes expected for those progeny would be comparable to InVigor® x Roundup Ready® canola or their parental GM canola lines. The control of glyphosate tolerant and glufosinate ammonium tolerant canola volunteers that occur as a result of gene transfer from InVigor® x Roundup Ready® canola crops represents an agricultural production issue with potential economic impact in terms of alternative weed management choices. There are a range of alternative herbicides assessed and approved by the APVMA which can be used to control GM canola volunteers (as described in Risk Scenario 2) in addition to mechanical means.
Gene transfer to non-GM herbicide tolerant canola
310. There are two conventionally bred herbicide-tolerant canola varieties currently being widely grown in Australia – triazine tolerant (TT) and imidazolinone-tolerant (Clearfield®). Where canola varieties that are tolerant to different herbicides are in close proximity, the production of multiple-herbicide resistant volunteers has been noted (Hall et al. 2000; Beckie et al. 2003; Knispel et al. 2008; Schafer et al. 2011). Gene transfer from InVigor® x Roundup Ready® canola to non-GM herbicide tolerant canola could result in the stacking of genes for tolerance to up to four different herbicide groups. Although InVigor® canola has not been commercially grown in Australia, this stacking of four herbicide tolerance traits has been a possibility since the approval of InVigor® canola and Roundup Ready® canola in 2003. Stacking was considered in the RARMPs for DIR 020/2002 and 021/2002 and was assessed to pose negligible risks. However, if InVigor® x Roundup Ready® canola were commercialised, development of canola plants with all four herbicide tolerance traits would be more likely, as it would require only two rather than three separate hybridisation events.
311. Apart from being tolerant to additional herbicides, such stacked GM canola is not expected to differ from the parental GM and non-GM varieties. There is no evidence or reasonable expectation that the non-GM herbicide tolerance traits would interact with the introduced genes from the GM canola proposed for release leading to changes in toxicity, allergenicity or weediness.
312. Multiple-herbicide tolerant individuals are as susceptible to alternative herbicides as are single-herbicide tolerant canola plants or their non-GM counterparts (Senior et al. 2002; Beckie et al. 2004; Dietz-Pfeilstetter & Zwerger 2009). In laboratory studies, multiple-herbicide tolerant canola plants were no more competitive than single-herbicide tolerant controls (Simard et al. 2005). Therefore, if multiple-herbicide tolerant canola plants were to occur, they are unlikely to be more invasive or persistent than non-herbicide tolerant or single-herbicide tolerant canola plants and could be controlled by other herbicides or other (non-chemical) agricultural practices. Triazine herbicides are in mode of action Group C, and imidazoline herbicides are in Group B. As discussed in Risk Scenario 2, there are a range of other herbicide products available with alternative or multiple modes of action.
313. Management of the impacts of gene transfer from InVigor® x Roundup Ready® canola to other canola can be achieved by the application of the already established principles and practices for minimising the development of herbicide resistance in any agricultural weeds: attention to the control of volunteers; informed selection and rotation of herbicides and crops; maintenance of hygiene in seeding, harvesting and transport operations; and implementation of good agronomic practices (Rieger et al. 2001; Downey 1999; Salisbury 2002c). These measures are incorporated in the Crop Management Plans that growers of InVigor® canola or Roundup Ready® canola are obliged to follow, and which will be implemented for InVigor® x Roundup Ready® canola.
314. While the control of canola with multiple herbicide tolerance traits may represent an agricultural production issue with potential economic impacts in terms of alternative weed management choices, there remains a range of approved herbicides and non-chemical methods of control.
315. Conclusion: The potential for allergenicity in people, or toxicity in people and other organisms, or increased weediness due to expression of the introduced genes in other canola plants as a result of gene transfer is not identified as a risk that could be greater than negligible. Therefore, it does not warrant further detailed assessment.
Risk scenario 4. Expression of the introduced genes in other sexually compatible plants
316. Transfer and expression of the introduced genes for herbicide tolerance and a hybrid breeding system in other sexually compatible plants could increase the weediness potential, or alter the potential allergenicity and/or toxicity of the resulting plants. As discussed in Risk scenario 1, the introduced genes do not encode proteins that are considered toxic or allergenic. Therefore, even if the introduced genes were to be transferred to, and expressed in, sexually compatible species, the recipient species would likely be no more toxic or allergenic than their unmodified precursors.
317. Under natural conditions, canola can cross with cultivated Brassica species (B. napus, B. juncea, B. rapa and B. oleracea) and, at very low frequencies, with three weed species important in Australia (R. raphanistrum, H. incana and S. arvensis) (Salisbury 2002b).
318. The risks associated with transfer of the introduced genes from the parental GM canola lines was previously assessed as very low to negligible, as summarised in Chapter 1, Section 5.6.2. The GM canolas proposed for release were produced by conventional breeding, and the potential for gene flow from them to compatible species, and the fitness of the resulting hybrids, is expected to be as low as for the parental GM canola lines.
319. The only difference in the consequence of gene flow from the GM canola proposed for release and the parental GM canola lines is the potential for the transfer of genes conferring tolerance to two herbicides in a single cross pollination event. This may confer a selective advantage in cultivated areas and non-cropped disturbed habitats where the corresponding herbicides are applied. However, these plants could be controlled using the range of alternative herbicides and non-chemical management techniques currently used in integrated weed management to control brassicaceous weeds and canola volunteers.
320. Conclusion: The potential for allergenicity in people, toxicity in people and other organisms or increased weediness due to the expression of the introduced genes in other sexually compatible plant species as a result of gene transfer is not identified as a risk that could be greater than negligible. Therefore, it does not warrant further detailed assessment.
2.4 Horizontal transfer of genes or genetic elements to sexually incompatible organisms
321. Horizontal gene transfer (HGT) is the stable transfer of genetic material from one organism to another without reproduction (Keese 2008). Data are accumulating to show that HGT is more widespread than previously believed and has been a significant force in the evolution of eukaryotic genomes (Bock 2010). In general, HGT between multicellular eukaryotes appears to be rare, occurring only on an evolutionary timescale, but has occurred between plants as well as between plants and less complex organisms (Bock 2010). All genes within an organism, including those introduced by gene technology, are capable of being transferred to another organism by HGT. HGT itself is not considered an adverse effect, but could be part of a scenario potentially leading to harm. A gene transferred through HGT could confer a novel trait to the recipient organism, through expression of the gene itself or by altering the expression of endogenous genes. The novel trait may result in negative, neutral or positive effects.322. Risks that might arise from horizontal gene transfer have been reviewed (Keese 2008) and considered in previous RARMPs (eg DIR 057/2004, DIR 085/2008 and DIR 091) which are available from the OGTR website or by contacting the Office. From the current scientific evidence, HGT from GM plants to other organisms presents negligible risks to human health and safety or the environment. This is due to the rarity of such events, relative to those HGT events that occur in nature, and the limited chance of providing a selective advantage to the recipient organism that would promote the spread and persistence of the transferred material.
323. Baseline information on the presence of the introduced or similar genetic elements is provided in Chapter 1, Section 7.2.3. All of the introduced genetic elements are derived from naturally occurring organisms that are already present in the wider Australian environment.
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Risk scenario 5. Presence of the introduced genetic material in other organisms as a result of horizontal gene transfer
324. Possible risks arising from HGT of the introduced genetic material to other organisms involves consideration of the potential recipient organisms and the nature of the introduced genetic material.
325. HGT could result in the presence of the introduced genes for herbicide tolerance, a ribonuclease and a corresponding ribonuclease inhibitor in bacteria, plants, animals or other eukaryotes. However, the introduced genes were isolated from common bacteria that are widespread in the environment (See Chapter 1, Section 7.2.3). It is far more likely that horizontal gene transfer will occur from naturally occurring B. amyloliquefaciens, S. hygroscopicus, S. viridochromogenes, O. anthropi or A. tumefaciens bacteria than from the GM canola plants.
326. In addition, the introduced genes are present in the parental GM canola lines already approved for commercial release. The bar, pat, and cp4 epsps genes are also present in GM cotton approved for commercial release (for example see DIR 062/2005, DIR 066/2006 and DIR 091). Therefore, the introduced genes are already available for HGT from the source organisms or commercially approved GM plants.
327. The likelihood of gene transfer was recently found to be negligible in studies on HGT of the cp4 epsps gene from GM canola to microorganisms during digestion in ruminants and during in vitro incubations (Sharma et al. 2004; Alexander et al. 2006; Reuter et al. 2007; EFSA 2009c).
328. Furthermore, the introduced bar, pat, cp4 epsps and goxv24 genes in the GM canola plants have been modified for plant codon usage, so in the unlikely event that gene transfer were to occur, only relatively low levels of gene expression in bacteria would be expected. The gene sequences expressed from the introduced genetic material are not expected to assist the process of HGT by facilitating gene movement across cell membranes or recombination with a host genome. Therefore, any rare occurrence of HGT of introduced genetic material to other organisms is not expected to persist and/or result in an adverse effect.
329. A key consideration in the risk assessment process should be the safety of the protein product resulting from the expression of the introduced gene rather than horizontal gene transfer per se (Thomson 2000). If the introduced genes, the encoded proteins or their end products are not associated with any risk then even in the unlikely event of HGT occurring, they should not pose any risk to humans, animals or the environment. Conclusions reached for Risk Scenarios 1 - 4 associated with the expression of the introduced genes did not represent an identified risk.
330. Conclusion: The potential for an adverse outcome as a result of horizontal gene transfer is not identified as a risk that could be greater than negligible. Therefore, it does not warrant further detailed assessment.