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ISIS Report 07/12/04

GM Sugar Beet Gone Sour

A new GM sugar beet event has been deregulated in the United States. But it is yet another story of poor assessment by the regulators that seriously threaten organic crops. Prof. Joe Cummins reports

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In October 2004, Monsanto Company (St. Louis, Missouri) and KWS SAAT AG (Einbeck, Germany) petitioned the Animal and Plant Health Inspection Service (APHIS), United States Department of Agriculture (USDA) for non-regulated status for their genetically modified (GM) sugar beet H7-1 made tolerant to the herbicide glyphosate [1].

Six years earlier, Novartis and Monsanto had already obtained non-regulated status for a sugar beet plant tolerant to glyphosate. The difference between H7-1 and the earlier Novartis-Monsanto strain is in a simplification of the genetic construction.

The earlier construction GTSB77 carried the gene coding for CP4 EPSPS, the uidA gene and a modified gox gene. The CP4 epsps and gox genes confer tolerance to the herbicide glyphosate and are derived from bacteria. The CP4 EPSPS is an enzyme not sensitive to applications of glyphosate, while the gox gene encodes the glyphosate oxidoreductase enzyme that degrades the herbicide. However, the gox gene was truncated during transformation and the 69% of the gene remaining is fused to sugar beet DNA, resulting in a chimeric gene. Although mRNA transcripts from this chimeric gox sequence are present in the sugar beet, no novel protein is translated (the gene does not make a protein) and the sugar beet does not have GOX enzyme activity .The uidA gene encodes beta-glucuronidase (GUS), which serves as a selectable marker [2, 3]. The sugar beet containing this bizarre patchwork of genes and inactive gene fragment was approved for commercial use in the United States (1998) and in Australia (2002) and has been widely grown.

Sugar beet H7-1 contains the CP4 epsps gene from the soil bacterium Agrobacterium, the modified figwort mosaic virus, chloroplast transit protein from Arabidopsis and the same terminator signal from pea employed in GTSB77. The difference between the two strains is that H7-1 does not have the inactive gox gene marker that was added to the earlier release [1].

The CP4 epsps gene has been used in a number of different glyphosate tolerant (Roundup Ready) crops such as maize, cotton soybean. Even though it is overtly stated in only a few petitions, the CP4 epsps gene used in GM crops is a synthetic approximation of the original bacterial gene, obtained by altering codons to the usage preferred in plants [4]. The synthetic genes bearing unique DNA sequences have not been tested for recombination or toxicity even though they are entirely new to evolution.

The petition for non-regulated status triggered an environmental assessment by USDA/APHIS. That review dealt with the spread of pollen from the transgenic crops to weedy relatives of the sugar beet and to neighbouring beet crops, and the danger of creating fertile weeds. As transgenic pollen may spread by at least as much as a kilometre from the production site (see following discussion), the matter is of concern to organic producers who may be penalized if their crop is contaminated by GM pollen. Even conventional producers have concerns about oppressive lawsuits from the patentee if their crop has been contaminated with transgenes. But USDA/APHIS provided cold comfort for the organic producers and barely mentioned conventional producers.

The USDA/APHIS comments are revealing: "The National Organic Program (NOP) administered by USDA’s Agricultural Marketing Service (AMS) requires organic production operations to have distinct, defined boundaries and buffer zones to prevent unintended contact with prohibited substances from adjoining land that is not under organic management. Organic production operations must also develop and maintain an organic production system plan…[that] enables the production operation to achieve and document compliance with the National Organic Standards, including the prohibition on the use of excluded methods. Excluded methods include a variety of methods used to genetically modify organisms or influence their growth and development by means that are not possible under natural conditions or processes…. Although the National Organic Standards prohibit the use of excluded methods, they do not require testing of inputs or products for the presence of excluded methods. The presence of a detectable residue of a product of excluded methods alone does not necessarily constitute a violation of the National Organic Standards. The unintentional presence of the products of excluded methods will not affect the status of an organic product or operation when the operation has not used excluded methods and has taken reasonable steps to avoid contact with the products of excluded methods as detailed in their approved organic system plan" [1].

USDA/APHIS seems to be saying that the responsibility for avoiding transgenic contamination of organic products rests solely with the organic producers and that it does not give any protection for those producers. However, when transgenic contamination is inevitable, as it is very likely to be the case, the organic producers may still claim that the contaminated crops are "organic". USDA/APHIS seems to be pushing for a declaration that transgenic contaminated crops can nevertheless be labelled "certified organic". Exporters of transgene contaminated crops will probably come up against a different viewpoint among their importers, where market rejection of GM crops is high.

The extensive spread of sugar beet pollen has been established in a number of studies. Using male-sterile test plants, production of transgenic offspring was clearly established at 200 metres beyond a hemp containment barrier and pollen spread in wind was as great as 1 kilometre [5]. Recombinant DNA from the sugar beet pollen has been detected in the soil at 50 meters from the test plot by PCR analysis and by natural transformation of a soil bacterium, Pseudomonas [6].

Recombinant DNA from transgenic sugar beet has also been detected in soil and by horizontal gene transfer for at least two years after planting the transgenic sugar beet [7]. Wild beet fertilized with pollen from transgenic beets stably inherited the transgenic trait [8]. Over-wintering of transgenic sugar beet was found to be a source for dispersal of transgenic pollen [9]. The problem of horizontal gene transfer in sugar beet has been discussed for several years [10] but is barely mentioned in USDA/APHIS reviews.

Finally, GM sugar beet was found to yield significantly less than high yielding conventional varieties [11]. Results of the UK Farm Scale Evaluations indicate that herbicide tolerant GM beet had more impacts on biodiversity than conventional beet [12].

In conclusion, USDA/APHIS seems to accept the widespread escape of recombinant genes from test plots and production facilities for GM sugar beet. Even though USDA has taken on the responsibility of certifying and regulating organic food production, it seems to be shedding that responsibility, even to the extent of apparently encouraging the sale of crops contaminated with transgenes under the organic label.

Clearly, USDA/APHIS cannot both promote GM crops and regulate organic crops. An independent regulator of GM crops is long overdue.

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