Assessment of genetic diversity of local varieties of cassava in tanzania using molecular markers

Twenty four arbitrarily selected cassava (Manihot esculenta Crantz) landraces, supplied by the germplasm collections in Kibaha and Ukiriguru research stations of Tanzania, were analysed by two different molecular marker techniques. Genetic distances on the basis of RAPD (random amplified polymorphic DNA) revealed separate clustering of almost all coast region-derived varieties. Inter-sequence-tagged repeat (ISTR) analysis, the second method, reproduced the geographical segregation, though the effect was less pronounced. Two genotypes were found to be very similar with either method, indicating a possible double accession. There is high overall genetic variability of the cassava germplasm. However, the variability is non- homogenous; rather it represents varieties of the same geographical origin grouped together. These findings are useful in the rationalisation of sampling and management of germplasm collections.