Page 36 - 19 Cotton SA September 2019

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TRACEABILITY OF GMO

COTTON (Bt-COTTON)

by Calvin Knight and Dr Annette Bennett, Cotton SA

Genetically modified organisms (GMOs) are seeds sensitivity), as they have a large amount
plants or crops that have had genes inserted into of DNA available. However, DNA analysis can
their genetic makeup in order to improve yield, also be done on fibre. Cotton lint is made up
quality or durability. According to a webinar, of 95% cellulose, but there is still a dehydrated
“DNA Analysis of GMO Cotton”, presented by cell nucleus within the fibres with enough sample
Dr Lothar Kruse from Impetus Bioscience, about material from which the DNA can be extracted.
64% of cotton worldwide is now GMO cotton. It is well known that DNA is specific for each
The International Service for the Acquisition species. The arrangement or sequence of the four
of Agri-biotech Applications (ISAAA Brief 53- nucleotides that DNA comprises of, determines
2017) listed global biotech cotton production at the nature and characteristics of the species.
24,21 million hectares in 2017. The presence of the Bt-gene can be determined
Consumers are interested in the traceability by means of a laboratory polymerase chain
of genetically modified organisms and their reaction (PCR) technique, where specific pieces
products. Recent work on cotton fibres has of DNA (in this case that of the Bt-gene) are
shown that Bt-cotton can be identified through proliferated or multiplied, and then sequenced
a standard technique used in general DNA and sent for identification to confirm the specific
analysis as used by most laboratories. For the arrangement of the nucleotides. In this case,
consumer interested in the cotton component of the Bt-gene’s DNA is made up of the four base
textiles this is good news. nucleotides with a specific arrangment in their
Bt-cotton has had the Bt-gene inserted complimentary amino-acid patterns.
into its general genetic make-up in order to DNA can be extracted by various procedures
improve resistance to bollworm pests, while the involving crushing or breaking down of cells
commercially available varieties now also show and chemical elution of DNA strands into
herbicide-tolerant traits. Bt-gene identification a solution. The solution is then placed in a
is commonly done on cottonseeds (1/10 000 thermocycler with primers that match the

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