I have been receiving calls regarding where grain can be tested for transgenic traits.
More and more, the grain handling industry is treating transgenic grain as an identity
preserved (IP) commodity. In order to segregate non-transgenic corn and soybean
grain, grain elevator managers want to know whether an incoming load of grain has
any transgenic grain mixed with non-transgenic grain. Ideally a qualitative transgenic
detection test is needed that will provide reliable results in the time it takes
a truckload of grain to move from the scale and probe to the dump pit. Perfecting
such a test with statistically accurate results is a monumental task. The grain
industry is not there yet, and can only provide specific tests for specific transgenic
traits.
A number of tests methods are available for testing each having pros and cons associated
with the methodology (Table 2). In general there are two scientific methods for
detecting transgenic field crops. One method involves testing for specific protein
that has been incorporated through biotechnology into a crop; the other is based
on detection of DNA sequences inserted in the crop.
Farmer testing of transgenic traits can easily be accomplished using lateral flow
strips (Table 3). Results with Lateral flow test strips are qualitative (yes or
no for presence of transgenic trait). A number of companies produce these strips
and they can be easily obtained (Table 4). Currently, there is no single, rapid or
inexpensive test to verify whether a crop or crop sample is free of transgenic traits.
Before purchasing a commercial test kit, it is best to know the specific crop and
transgene to be tested.
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Table 2. Methods to test for transgenic traits, their cost, duration ease of use
and expected results.
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Method
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Tests for
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Cost/Sample
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Duration
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Ease of Use
|
Results
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Bioassay
(For herbicide resistant traits)
|
Tolerance to chemical
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$10-12
|
5-7 days
|
Moderate; requires familiarity with laboratory practices
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Quantitative measure for presence of herbicide resistance
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ELISA
(Enzyme-Linked Immunosorption Assay)
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Protein
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$75-100 a
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2-4 days d
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Moderate; requires familiarity with laboratory practices and some specialized equipment
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Quantitative measurement of protein levels
|
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Lateral Flow Strip
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Protein
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$8-10 b
|
10-20 minutes
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Little training and no sophisticated lab equipment required
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Qualitative measurement of presence or absence of target protein analyte
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PCR
(Polymerase Chain Reaction)
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DNA
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$200-600 ac
|
5-14 days d
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Difficult; requires specialized equipment and training
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Qualitative/semi-quantitative measurement of levels of target sequence
|
|
Southern Blot
|
DNA
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$100-300
|
4-6 days
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Difficult; requires specialized training and equipment including radioactive materials
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Identifies specific DNA sequences
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a Estimated cost of analysis performed by a commercial testing laboratory
b Estimate cost of material to perform on-site analysis, excluding labor
c Prices for PCR tests vary widely and depend on the nature of the test
being performed (e.g., screening versus quantitative assessment) d Estimate
of time required to have samples analyzed by a commercial testing laboratory. Sources:
Gene Amberson and www.croplifeamerica.org/public/issues/biotech/detecta.pdf
(website verified 15 October 2003)
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Table 3. Transgenic detection kits submitted to Grain Inspection, Packers and Stockyards
Administration (GIPSA) of the Federal Grain Inspection Service by kit manufacturers.
Kit performance as claimed by the manufacturer was verified by GIPSA.
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Company
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Test Kit
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Part Number
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Event/Protein Analyte
|
Test Sensitivity
|
Test Format
|
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Agdia, Inc.
|
Roundup Ready® ImmunoStrip(TM)
|
STX- 74000
|
Roundup Ready Protein CP4EPSPS
|
1 in 800
corn kernels
|
Lateral Flow Strip
|
|
EnviroLogix Inc.
|
Cry9C
ELISA Plate Kit, High Sensitivity Protocol
|
AP 008
|
StarLink/Cry9C
|
1 in 10,000 corn kernels
|
Microtiter Well Plate Assay
|
|
EnviroLogix Inc.
|
Cry9C
ELISA Plate Kit, Rapid Protocol
|
AP 008
|
StarLink/Cry9C
|
1 in 2,400 corn kernels
|
Microtiter Well Plate Assay
|
|
EnviroLogix Inc.
|
QuickStix (TM) Strips for Cry9C (StarLink)
|
AS 008 BG
|
StarLink/Cry9C
|
1 in 800 corn kernels
|
Lateral Flow Strip
|
|
EnviroLogix, Inc.
|
QuickStix (TM) Strips for Roundup Ready® in Soybeans
|
AS 010 BG
|
Roundup Ready® protein,CP4 EPSPS
|
1 in 1,000 soybeans
|
Lateral Flow Strip
|
|
EnviroLogix, Inc.
|
QuickStix (TM) Strips for Roundup Ready® in Corn
|
AS 010 BG
|
Roundup Ready® protein,CP4 EPSPS
|
1 in 200 corn kernels
|
Lateral Flow Strip
|
|
EnviroLogix Inc.
|
QuickStix (TM) Kit for YieldGard® Rootworm Bulk Seed
|
AS015BG
|
Cry3Bb
|
1 in 200 corn kernels
|
Lateral Flow Strip
|
|
Neogen Corporation
|
Agri-Screen CP4 Strip Test
|
8005
|
CP4 EPSPS protein of Roundup Ready soybean and Roundup Ready corn (NK603)
|
1 in 800 corn kernels 1 in 1,000 soybeans
|
Lateral Flow Strip
|
|
Neogen Corporation
|
Agri-Screen Qualitative Cry9C Test
|
8002a
|
StarLink/Cry9C
|
1 in 800 corn kernels
|
Microtiter Well Plate Assay
|
|
Neogen Corporation
|
Agri-Screen Cry9C Strip Test
|
8003
|
StarLink/Cry9C
|
1 in 800 corn kernels
|
Lateral Flow Strip
|
Strategic
Diagnostics, Inc.
|
GMO TM Bt9 Maize Kit
|
7110030
|
StarLink/Cry9C
|
1 in 10,000 corn kernels
|
Microtiter Well Plate Assay
|
Strategic
Diagnostics Inc.
|
GMO Quick TM Bt9 Test Kit
|
7110020
|
StarLink/Cry9C
|
1 in 800 corn kernels
|
Microtiter Well Plate Assay
|
Strategic
Diagnostics Inc.
|
Trait Bt9TM
|
7000034
|
StarLink/Cry9C
|
1 in 800 corn kernels1
|
Lateral Flow Strip
|
Strategic
Diagnostics Inc.
|
Trait Bt9TM
|
7000003
|
StarLink/Cry9C
|
1 in 800 corn kernels
|
Lateral Flow Strip
|
Strategic
Diagnostics Inc.
|
Trait Bt9TM
|
7000012
|
StarLink/Cry9C
|
1 in 800 corn kernels
|
Lateral Flow Strip
|
|
Strategic Diagnostics, Inc.
|
TraitTM Cry3Bb Corn Grain Test kit
|
7000041
|
Cry3Bb (YieldGard Rootworm®)
|
1 in 800 corn kernels
|
Lateral Flow Strip
|
Strategic
Diagnostics, Inc.
|
Trait RUR Bulk Soybeans 5-Minute Test Kit
|
7000014
|
Roundup Ready Soybeans/CP4 EPSPS
|
1 in 1,000 soybeans
|
Lateral Flow Strip
|
Strategic
Diagnostics, Inc.
|
Trait RUR NK603 Corn Grain 5-Minute Test Kit
|
7000011
|
Roundup Ready Protein CP4 EPSPS
|
1 in 800 corn kernels
|
Lateral Flow Strip
|
Strategic
Diagnostics Inc.
|
TraitTM Bt1F
Corn Grain Test Kit
|
7000018
|
Cry1F
(HerculexTM)
|
1 in 600 corn kernels
|
Lateral Flow Strip
|
|
1/ Sensitivity of 1 in 400 kernels requires a 10-minute development
time. Sensitivity of 1 in 800 kernels requires a 20-minute development time.
Source: http://www.usda.gov/gipsa/
Click on "Tech Services/Support" (website verified 15 October 2003)/
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