What is Genetic Engineering?
In a very short period of time, advances in genetic engineering have created tremendous potential for rapid introduction of traits in a myriad of food and feed crops. Although the technologies for identification and isolation of specific gene sequences are highly sophisticated and precise, the techniques for inserting desired genes in a plant’s DNA are still evolving. They require extensive testing to confirm that the desired gene transfers have been made and that resulting seed stock will express the desired traits at adequate levels.
There are a number of genetically engineered (“GE”) foods in the marketplace, consumers, government agencies, and food retailers in many countries are rapidly gaining awareness and voicing concerns. In some cases, they are demanding labeling –for the ability to distinguish genetically modified organisms (GMOs) or foods from other foods. In some areas, such as parts of Europe and the Pacific Rim, some consumer groups are seeking to ban GMOs altogether until the potential corollary effects are better understood. Threshold levels are being established in some countries to set maximum levels for GMOs in certain foods or crops.
Why Test for GMOs?
Labeling requires knowledge of the genetic status of all ingredients and segregation and identity preservation of GMO and non-GMO ingredients as they move through the grain distribution channels and into food production. This segregation requires tracing back to the seed level and upward through the processing and distribution chain to retail consumption. Testing for genetic markers also includes testing crops during the growing cycle to ensure that no cross- pollination occurs between GE seeds and non-GE seeds of the same crop.
To date, the largest applications of genetic engineering in agriculture have concentrated on the high volume crops: corn, soybeans, cotton, alfalfa and canola. The principal modifications have centered on two different aspects of pest control: i) introduction of a protein produced by the Bacillus thurigiensis (Bt) bacteria into seeds for ingrained insecticide protection, and ii) resistance to the synthetic herbicides such as glyphosate (RoundUp®) in so-called RoundUp Ready seeds or glyphosinate in LibertyLink® seeds. There have been numerous different insect resistant varieties developed utilizing unique Bt gene segments, and thereby expressing different and specific proteins including Cry1Ab, Cry1Ac, Cry1C, Cry1F, Cry2A, Cry3B, Cry34 and Cry9C. Regardless of the protein expressed, these different Bt varieties enable the plant to produce its own internal protection against pests such as the European corn borer in the case of corn plants, or against the boll weevil in the case of cotton plants. Similarly, Bt varieties have been developed for other crops such as potatoes and rice. The herbicide tolerant varieties on the other hand, render the plant resistant to powerful herbicides such as glyphosate (RoundUp) or glyphosinate (Liberty®). This enables the grower to apply herbicides in a more targeted and efficient manner without harming the crop.
Some of these varieties have received regulatory approvals in different countries by international regulatory agencies for specific applications, while others await final resolution and action. Concerns in Europe and parts of Asia have slowed the process of regulatory approvals, which has created the need for further segregation of grain and food ingredients destined for export, in order to comply with different international restrictions.
How Are GMOs Detected?
A 96-well ELISA plate form of the assay is designed for quantitative, high volume, laboratory based testing where certain immunoassay equipment is on-hand and useful in large-scale screening and documentation. The lateral flow membrane formats (LFDs) are also suitable for high volume screening, but are especially designed for use in the field, with no additional equipment or facilities required. The next advancement in molecular GMO detection will be the emergence of more robust, rapid DNA-based testing. Previously, these molecular methods, like PCR (polymerase chain reaction), were time consuming, expensive, and exclusive to centralized laboratories. With the emergence of new technology, GMO DNA testing can be more accessible, rapid, and user-friendly.
