GM Crop Database

Database Product Description

A2704-12, A2704-21, A5547-35 (ACS-GMØØ5-3, ACS-GMØØ4-2, ACS-GMØØ8-6)
Host Organism
Glycine max (Soybean)
Trait
Herbicide tolerant, glufosinate ammonium.
Trait Introduction
Microparticle bombardment of plant cells or tissue
Proposed Use

Production for human consumption and livestock feed.

Product Developer
Bayer CropScience (Aventis CropScience(AgrEvo))

Summary of Regulatory Approvals

Country Food Feed Environment Notes
Argentina 2004 2004 2011
Australia 2004
Brazil 2010 2010 2010 View
Canada 2000 2000 1999 View
China 2007 2007 View
Colombia 2014 2012
European Union 2008 2008 View
Japan 2002 2003 1999 View
Korea 2009 2009 View
Malaysia 2012 2012
Mexico 2003 2003
Philippines 2009 2009 View
Russia 2008 2007
Singapore 2014 View
South Africa 2001 2001 View
Taiwan 2007 View
United States 1998 1998 1996
Uruguay 2012 2012 2012
Vietnam 2015 2015 View

Introduction Expand

The genetically modified soybean lines A2704-12, A2704-21, and A5547-35 expresses the phosphinothricin-acetyl-transferase (PAT) protein that confers tolerance to the active ingredient L-phosphinothricin in glufosinate ammonium. The expression of PAT is due to the introduction of the pat gene from Streptomyces viridochromogenes, a gram-positive soil bacterium.       

Glufosinate ammonium is a post-emergence, broad-spectrum contact herbicide and plant dessicant.  L-Phosphinothricin was first isolated as bialaphos, an antibiotic synthesized during the fermentation of Streptomyces viridochromogenes or S. hygroscopicus. In herbicidal formulations it is a component of glufosinate ammonium, which is chemically synthesized. Glufosinate ammonium is a racemic mixture of L-phosphinothricin, the herbicidal active moiety, and its D-enantiomer.  L-Phosphinothricin is structurally similar to glutamate, the substrate of glutamine synthetase (GS), an enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia. L-phosphinothricin inhibits the activity of GS irreversibly by binding to its active sites. The inhibition of GS caused by the application of glufosinate ammonium to plants results in the accumulation of ammonia, the reduction in the levels of glutamine, and the inhibition of photosynthesis, all of which results in the death of the plant. Plants transformed with the pat gene can express the enzyme phosphinothricin-acetyl-transferase (PAT) which acetylates L-phosphinothricin into a non- phytotoxic metabolite (N-acetyl-L-glufosinate).

Summary of Introduced Genetic Elements Expand

Code Name Type Promoter, other Terminator Copies Form
pat phosphinothricin N-acetyltransferase HT

Cauliflower mosaic virus 35S

Cauliflower mosaic virus 35S poly-A signal

2

Synthetic gene version of native enzyme

Characteristics of Glycine max (Soybean) Expand

Center of Origin Reproduction Toxins Allergenicity

Southeast Asia; wild soybean species endemic in China, Korea, Japan, Taiwan.

Self-polinated; rarely displays any dormancy characteristics; does not compete well with other cultivated plants.

Raw soybeans contain trypsin inhibitors, which are toxin when eaten.

Soy allergies are common, and eating soy products can cause rashes and swelling of the skin in sensitive individuals.

Donor Organism Characteristics Expand

Latin Name Gene Pathogenicity
Streptomyces viridochromogenes pat

S. viridochromogenes is ubiquitous in the soil. It exhibits very slight antimicrobial activity, is inhibited by streptomycin, and there have been no reports of adverse affects on humans, animals, or plants.

Modification Method Expand

The soybean event A2704-12 was produced via the particle acceleration method using a pUC19 based vector pB2/35SAcK containing a modified form of the pat gene under the control of promoter and termination sequences derived from cauliflower mosaic virus.

The nucleotide sequence of the pat gene was altered via site-directed mutagenesis in order to reduce the high G:C content (typical for bacterial genes but atypical for plant genes) and generate plant-preferred codons. These sequence modifications did not result in changes to the predicted amino acid sequence of the PAT protein.

Characteristics of the Modification Expand

Inserted DNA:  Southern blot analysis of genomic DNA from line A2704-12 indicated the incorporation at one locus in the nucleic chromosome. It shows two copies of the pat gene are inserted in a head-to-tail configuration, one copy of the 3' bla sequences and one copy of the 5' bla sequences were integrated between the two pat gene copies.

Expression:  The PAT protein was expected to be expressed in all tissues of the plant since the pat gene cassette contains the CaMV 35S promoter (P35S from cauliflower mosaic virus).  The levels of PAT protein expression were quantitated using enzyme linked immunosorbent assay (ELISA). For A2704-12 the following amounts were measured: 2,3 x 10-3 %, 1,0 x 10-3 % and 3,2 x 10-4 % of the total crude protein in samples of forage, hay and seed, respectively. No PAT protein was detected in toasted soybean meal, crude lecithin, refined oil, and refined bleached and deodorised oil (food grade soybean oil) prepared from A2704-12.

Environmental Safety Considerations Expand

Field Testing

Transgenic soybean lines A2704-12, A2704-21, and A5547-35, were field tested in the United States (1990-1993) and line A2704-12 was field tested in Canada. Field trial reports from these tests demonstrated that the transformed lines did not exhibit weedy characteristics, and had no effect on nontarget organisms or the general environment.

Outcrossing

Soybean (Glycine max) is considered a self-pollinating species, with the amount of crosspollination to other soybean (Glycine max) generally considered to be less than 1%. This low probability of outcrossing is recognized in the planting guidelines for the production of certified seed.  Furthermore, the reproductive characteristics such as pollen production and viability were unchanged by the genetic modification resulting in A2704-12.

Cultivated soybean, Glycine max, naturally hybridizes with the wild annual species G. soja. Although G. soja is endemic to China, Korea, Japan, Taiwan and the former USSR it is not naturalized in North America, although it may possibly be grown in research plots. It was concluded that the potential for transfer of the herbicide tolerant trait from the transgenic lines to soybean relatives through gene flow was negligible in managed ecosystems, and that there was no potential for transfer to wild species in Canada and the continental United States.

Weediness Potential

The pat gene that confers tolerance to the herbicide, glufosinate, will not provide soybean line A2704-12 or its progeny, with any measurable selective advantage over nontransformed soybean plants in their ability to disseminate or to become established in the environment.  Tolerance to glufosinate ammonium will not, in itself, render soybean weedy or invasive of natural habitats since none of its reproductive or growth characteristics have been modified. The glufosinate ammonium tolerant plant would easily be controlled by mechanical means or by using alternative herbicides. Cultivated soybean is highly unlikely to establish in non-cropped habitats and there have been no reports of soybean surviving as a weed or exhibiting weed-like characteristics. It was concluded that soybean line A2704-12 has no altered weed or invasiveness potential compared to commercial soybean varieties.

Secondary and Non-Target Adverse Effects

Field observations of soybean lines A2704-12, A2704-21, and A5547-35 concluded there was no significant adverse impact on organisms beneficial to plants or agriculture, or on other nontarget organisms. These events were not expected to impact on threaten or endangered species as the PAT enzyme is not known to have any toxic properties. The high specificity of the enzyme for its substrates makes it unlikely that the introduced enzyme would metabolize endogenous substrates to produce compounds toxic to beneficial organisms.

Impact on Biodiversity

Soybean lines A2704-12, A2704-21, and A5547-35 have no novel phenotypic characteristics that would extend their use beyond the current geographic range of soybean production. Since there are no wild relatives of soybean in Canada and the continental United States and since soybean is not an invasive species, the novel trait will not be transferred to plant species in unmanaged environments.

Food and/or Feed Safety Considerations Expand

Nutritional Data

Samples of hay, forage, seed, hulls, and toasted and non-toasted defatted soy meal from transgenic soybean were subjected to proximate analyses (moisture, crude protein, crude fat, ash, acid detergent fibre, neutral detergent fibre, carbohydrate). As well, seed samples were subjected to fatty acid analysis, amino acid analysis, analyses of minerals, vitamins, bioactive compounds, such as isoflavones and phosphatides, and anti-nutrients, such as stachyose, raffinose, phytic acid, trypsin-inhibitors, and lectins.

Soybean A2704-12 is found to be compositionally and nutritionally equivalent to its traditional non-transgenic counterpart and to other current commercial soybean varieties.

There is no impact on the nutritional value of the soybean seeds caused by the genetic modification.

Toxicology

Samples of seed were analyzed for stachyose, raffinose, and phytic acid, and additionally for trypsin inhibitor and lectins. The concentrations of phytoestrogens, such as daidzein, genistein, and glycitein, were determined for samples of seed, and toasted and non-toasted soy meal. The levels of these compounds were not statistically different between samples from non-transgenic and transgenic soybeans.

Allergenicity

The low potential for allergenicity of the PAT protein has previously been established through amino acid sequence comparisons with known protein allergens and digestability studies using simulated gastric and intestinal fluids. Additionally, soybean seed extracts from line A2704-12 and from non-transgenic control plants were screened against a panel of sera from 16 soy-allergic individuals using the radioallergosorbent test (RAST). The results of this study did not reveal any qualitative or quantitative difference in endogenous soybean allergen content between transgenic and non-transgenic soybean.

Abstract Collapse

Soybean (Glycine max) is grown primarily for its seed, which has many uses in the food and industrial sectors, and represents one of the major sources of edible vegetable oil and of proteins for livestock feed use. The major producers of soybeans were the United States, Brazil, Argentina, China, India, Paraguay and Canada.

A major food use of soybean in North America and Europe is as purified oil, used in margarines, shortenings, and cooking and salad oils. It is also a major ingredient in food products such as tofu, tempeh, soya sauce, simulated milk and meat products, and is a minor ingredient in many processed foods. Soybean meal is used as a supplement in feed rations for livestock.

Weeds are a major production problem in soybean cultivation. Typically, weeds are managed using a combination of cultural (e.g. seed bed preparation, using clean seed, variety selection, and planting date) and chemical controls. Depending on the production area and the prevalent weed species, herbicides may be applied before planting (e.g. pendimethalin, trifluralin, metribuzin), after planting but before emergence (e.g. pendimethalin, linuron, imazethapyr), and/or after emergence (e.g. bentazon, acifluorfen, fomesafen). Commonly, several different herbicides are required to adequately control weeds in soybean fields.

The soybean lines A2704-12, A2704-21, and A5547-35 were developed to allow for the use of glufosinate ammonium, the active ingredient in phosphinothricin herbicides (Basta® , Ignite® , Rely® , Liberty® , Harvest® , and Finale®) as a weed control option. These genetically engineered soybean lines contain the fungal enzyme phosphinothricin-N-acetyltransferase (PAT) that allows these plants to survive the otherwise lethal application of glufosinate. The pat gene inserted into A2704-12, A2704-21, and A5547-35 was isolated from a common soil fungus, Streptomyces viridochromogenes, and introduced into the soybean genome by particle acceleration (biolistic) transformation.

The PAT enzyme in soybean lines A2704-12, A2704-21, and A5547-35 converts L-phosphinothricin (PPT), the active ingredient in glufosinate ammonium, to an inactive form thereby conferring resistance to the herbicide. In absence of PAT, application of glufosinate leads to reduced production of the amino acid glutamine and increased ammonia levels in the plant tissues which are lethal to the plant. The PAT enzyme is not known to have any toxic properties.

Glufosinate-tolerant soybean lines A2704-12, A2704-21, and A5547-35 were tested in field trials in the United States (1990-1993) and line A2704-12 was field tested in Canada and Japan. These tests demonstrated that the transformed lines did not exhibit weedy characteristics, or negatively affect beneficial or nontarget organisms, and were not expected to impact on threatened or endangered species.

Soybean does not have any weedy relatives with which it can crossbreed in the continental United States or Canada. Cultivated soybean can naturally cross with the wild annual species G. soja, however G. soja, which occurs naturally in China, Korea, Japan, Taiwan and the former USSR, is not naturalized in North America. Additionally, soybean plants are almost completely self-pollinated and reproductive and growth characteristics remained unchanged by the genetic modification resulting in glufosinate-tolerant soybean lines. It was therefore concluded that the potential for transfer of the glufosinate tolerance trait from the transgenic line to soybean relatives through gene flow (outcrossing) was negligible in managed ecosystems, and that there was no potential for transfer to wild species in Canada and the continental United States.

The food and livestock feed safety of glufosinate-tolerant soybean lines A2704-12, A2704-21, and A5547-35 was established based on the lack of toxicity or allergenicity of the PAT protein and by direct laboratory analyses. The nutritional equivalence and wholesomeness of these soybeans compared to conventional (non-GM) soybeans was demonstrated by the analysis of key nutrients, including proximates ( e.g., moisture, crude protein, crude fat, ash, acid detergent fibre, neutral detergent fibre, carbohydrate), fatty acid analysis, amino acid analysis, and analyses of minerals (calcium, phosphorous, and potassium). This equivalence of glufosinate-tolerant soybeans to conventional soybeans was further confirmed in feeding studies with rats and broiler chickens.

Links to Further Information Expand

Canadian Food Inspection Agency Comissão Técnica Nacional de Biossegurança - CTNBio (Brazil) European Commission Food Standards Australia New Zealand Health Canada Japanese Biosafety Clearing House, Ministry of Environment Secretariat of Agriculture, Livestock, Fisheries and Food Argentina U.S.Department of Agriculture, Animal and Plant Health Inspection Service US Food and Drug Administration USDA-APHIS Environmental Assessment Uruguay National Biosafety

This record was last modified on Tuesday, September 6, 2016