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There
is considerable movement of material into and out
of the International Cocoa Genebank, Trinidad (ICG,T),
which could potentially result in the misplacement
of cacao material. As overseer of this important
cacao germplasm collection, CRU is systematically
checking accessions in the ICG,T,
to confirm the identity of already established accessions
and therefore avoid mistakes in identity of material
used in research, and material distributed to the
cocoa community world-wide. The increasing transfer
of material among different countries necessitates
careful attention to accurate labelling if research
objectives are to be met, and results are to be
trusted and transferable.
Verification
employs the use of two techniques established at CRU.
The first, morphological descriptors,
looks at the material at the phenotypic level; the
second, Molecular analysis (such as RAPD or SSR),
examines it at the molecular level. In combination
these techniques provide a verification system that
affords a high degree of confidence to users of
the ICG,T.
At the first level of description, putative true-type
trees are labelled based on their flower, fruit,
and leaf characteristics. These types are
then analysed using RAPD analysis to generate a
DNA fingerprint for each tree, which reflects the
polymorphism at 23 loci in T. cacao. Where
possible, the DNA fingerprint is compared with that
of the original tree from which it was propagated.
Where a DNA fingerprint matches that obtained for
the original tree at all 23 loci, it is said to
be a true-type.
CRU
aims to confirm at least four true-type trees per
plot for every accession in the ICG,T,
working initially from a priority list of clones
known to have useful traits, such as disease resistance,
good quality characteristics and/or good yield potential.
Project Staff
Lambert Motilal
Frances Bekele
Gillian Bidaisee
Junior Bhola
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