Page 37 - 19 Cotton SA September 2019

/ PRODUCTION AND TECHNOLOGY

sequences that one is looking for. By making traced with the new “DNA string“ arrangement,
use of Taq polymerase, the DNA template (from which would then identify the foreign piece of
the cotton fibre with the primers attached to the DNA.
specific region of the foreign Bt-material) are By making use of this PCR technique, it is
elongated and extended to provide enough possible to identify GMOs in cottonseed and in
material for further identification. This is the the fibre if it is present. This is an advantage for
basic premise of PCR. breeding programmes and in research protects
to ensure that new cultivars carry the Bt-gene.
Plant DNA n 35s promoter n CTP2 gene n CRY gene Unknown seed or fibre could also be analysed
n NOS terminator n Plant DNA with this method to determine if it is GMO cotton
(although determining the cultivar can also
Depicted above is an overview of the section provide this information).
of the plant DNA strand where the foreign gene It should be noted that once lint has been
(CRY gene)would be inserted. PCR will be able spun, dyed and treated with heat or chemicals,
to target the specific nucleotide sequences on most of the DNA will have been destroyed, so
either side of this specific DNA region. the analysis must be done on raw cotton fibre.
Screening is done to identify any GMO insert Dyes interfere with the PCR technique and will
by detecting the 35s promoter, the CTP2 gene, not give reliable results.
the CRY gene, the terminator, and the plant The possibility to detect GMO in cotton fibre
DNA. The PCR product with the specific foreign is now officially recognised.
DNA is then sequenced and compared to a
standard database (e.g. Basic Local Alignment Reference:
Search Tool [BLAST]) of known organisms with a IWA 32:2019 Preview. Screening of genetically modified
similar nucleotide pattern. A specific similarity is organisms (GMOs) in cotton and textiles.

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Volume 21 No 3 September 2019 | 37