Background information:

Due to the recent prevalence of genetically modified crops, strict regulatory and control systems are in need. A key to these systems is the detection of whether a plant is a GMO (genetically modified organism) and what type of genetic modification was done. This diagnosis is important to both regulatory bodies and laboratories: the former to determine proper labeling and information to consumers, and the latter to ensure that their genetically modified crops produces the engineered phenotype.

There are currently two prevalent types of genetically modified plants: insect-resistant plants and herbicide resistant plants. Our company’s current research and development is focused on the detection of insect-resistant crops. These plants contain recombinant DNA with a gene (the “Cry” gene) found in the soil bacterium Bacillus Thurigiensis (BT). This gene encodes crystal proteins (commonly known as “Cry” proteins) that are natural insecticides. There are numerous types of insect-resistant varieties developed with different segments of the Cry gene. The unique segments express different proteins, which are classified by insect-specificity and amino acid sequence. The most widely used segments in GM plants are the BT Cry1AB and Cry1AC.

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The grains of such GM crops can be identified by either detecting the presence of the Cry protein, or by detecting the presence of the Cry gene (recombinant DNA). The current market methods are listed below with their advantages and disadvantages:

Polymerase Chain Reacion (PCR): PCR is a laboratory-based DNA detection technique.

Advantage:

(1) detects the Cry gene (DNA)
(2) extremely sensitive

Disadvantage:

(1) requires trained staff and specialized equipment.
(2) high amount of false positives due to extreme sensitivity
(3) Very long sample analysis time (requires approximately one day or longer to receive results from a testing lab)
(4) Relatively expensive to run: Per sample costs can range from less $100 to greater than $300.

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Enzyme-linked Immunoassay (ELISA): ELISA is a laboratory-based protein detection technique.

Advantage:

(1) detects the Cry protein
(2) relatively easy to perform
(3) relatively inexpensive compared to PCR

Disadvantage:

(1) requires trained staff and specialized equipment
(2) lowered sensitivity
(3) relatively long analysis time (4-24 hrs)
(4) shelf life is relatively short (6 months at 4° C)

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Lateral Flow test strips (Rapid tests): Rapid tests detect protein presence like ELISA.

Advantage:

(1) detects the Cry protein
(2) very easy to perform
(3) inexpensive (only about 1/3 of the cost of ELISA)
(4) requires no trained staff of specialized equipment
(5) can be used in fields, grain elevators, or labs

Disadvantage:

(1) lower sensitivity than PCR (but less false positives).
Due to the overwhelming advantages of utilizing lateral flow test strips, many corporations and regulatory bodies have now recognized rapid tests as the standard method to detect transgenic traits.

The lateral flow rapid test technology in application to GMO is relatively new though, and our company’s mission is to make the rapid tests as accurate and as cost-effective as possible. One of the our pioneering developments is the incorporation of buffers into our rapid tests, so that clean tap water would be the only reagent required to test crop grains (previously, buffers needed to be added to grains to extract Cry proteins for detection). This development will allow easier use in the field.

Please refer to our catalog for this innovative product.