Biotechnology

I. DNA fingerprinting of cocoa accessions:

Characteristic DNA fingerprints/band profiles have been developed for all accessions using RAPD markers. Of the 40-decamer primers tested, 12 decamer primers produced reproducible and consistent bands. The remaining 28 primers produced no bands or inconsistent bands, which are unsuitable for evaluation. Twelve primers were found to be polymorphic between the accessions tested and were used for RAPD analysis to distinguish cocoa accessions. Using these twelve polymorphic primers, fingerprints have been developed for all the accessions. Fingerprints serve as the reference map for identifying the accessions.

Nigerian accessions

Primers OPB 01,OPB 06, OPB 12, OPC 07, OPC12, OPC 18 and OPC 19 produced cent per cent polymorphism. Primers OPC 02 produced mostly monomorphic bands and less no. of polymorphic bands of 37.5% polymorphism.

Four accession specific unique bands were identified using decamer primers. Primer OPC 02 produced single unique band-200bp in N 31, which distinguished this from rest of the accessions. Primer OPC 09 produced 300 bp unique band in N 23. Primer OPC 13 produced unique high molecular weight band, 2100 bp in N 10. Primer OPC 18 produced single unique band of 250 bp N 35.

Lalbagh accessions

Primers OPB 10, OPB 12, OPC 07, OPC 09, OPC 12, OPC 13 and OPC 18 produced unique polymorphic marks. Primer OPB 10 produced 2 unique bands- 250bp in NA 31 and 275bp in ICS 1, which distinguish these two from the rest of accessions. Primer OPB 12 produced 740 bp unique band in ICS 6. Primer OPC 7 produced unique high molecular weight band in ICS 6. Primer OPC 09 produced two unique bands of 500bp and 480bp in SCA 12. Primer OPC 12 produced 1400bp in SCA 6 and 1250 bp in SCA 6 and 1250 bp in NA 31 and 800bp in NA 31. Primer OPC 13 produced two unique bands 1200bp in SCA 6 and 950 bp in NA 31. Primer OPC 18 produced single unique band, 800bp in NA 33. Primers OPB 1, OPB 6, OPC 5, OPC 12 and OPC 13 have produced cent per cent polymorphism while OPC 2 produced mostly monomorphic bands with low polymorphism of 28.57%.

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