Production of genetically modified (GM) crops is currently concentrated in just a
few countries while more countries are experimenting new traits. For 2003, 99% of
GM crops are produced in four countries, i. e. US 63%, Argentina 21%, Canada 6%,
Brazil and China 4%. Crop-wise, GM soybean made up 61% of global area and GM
corn accounts for 23% followed by GM cotton (11%) and GM canola (5%).
Compared with the global planting area, GM soybean and cotton accounted for 55%
and 21%, respectively. Two major GMO traits in 2003 were herbicide tolerant crops,
accounted for 73% of all GM crops, while Bt crops accounted for 18%.
Legislation enacted worldwide to regulate the presence of genetically modified
organisms (GMOs) in crops, foods and inGREdients, necessitated the development of
reliable and sensitive methods for GMO detection. In this article, protein- and
DNA-based methods employing western blots, enzyme-linked immunosorbant assay,
lateral flow strips, Southern blots, qualitative-, quantitative-, real-time- and limiting
dilution-PCR methods, are discussed. Where information on modified gene sequences
is not available, new approaches, such as near-infrared spectrometry, might tackle the
problem of detection of non-approved genetically modified (GM) foods. The
efficiency of screening, identification and confirmation strategies should be examined
with respect to false-positive rates, disappearance of marker genes, increased use of
specific regulator sequences and the increasing number of GM foods.
In Taiwan all foods containing more that 5% GMO must be labeled, and the
DNA-based methods are the most popular ones. Typical detection methods are the
following: Western blots, Enzyme-Linked Immuno-Sorbant Assay (ELISA), Lateral
flow strips, Southern blots, real-time- and limiting dilution-PCR methods being this
last one the most commonly used. Significant efforts are underway to identify proper
detection methodology for GMO content in fermented food from soybean, i.e. miso
and sufu. Standard PCR and nested PCR cannot give positive results to the detection
of the transgenic components in miso. Standard PCR system failed to detect Roundup
ReadyTM soybean (RRS) in sufu, while nested PCR can detect RRS in sufu.
