Mzena, Geradina Pantaleo2026-03-132026-03-132010https://www.suaire.sua.ac.tz/handle/20.500.14820/7415DissertationEvaluation for effectiveness of new expressed simple sequence repeat (ESSR) marker is an important component in the genetic improvement of cassava crop for agricultural development. ESSRs are often the markers of choice for genetic studies and identification of CBSD resistance. This study was aimed at: (i) Determining the optimum PCR conditions on annealing temperature and MgCh concentrations, ii) Identifying polymorphic loci for ESSR markers for genetic studies of cassava (iii) Identifying polymorphic loci of ESSR markers linked to CBSD. PCR amplification of each ESSR locus was optimized for annealing temperature and MgCh concentration. Variation at each ESSR locus was assessed in 24 cassava genotypes from 11 different countries all over the world. Successful amplification was achieved from a total of 68 primer pairs of which 53 showed polymorphism within the diversity of cassava genotypes panel. A total of 231 alleles were observed with an average of 4.35 alleles per marker and a range of 2 to 11 alleles. The PIC values measured by the frequency of alleles ranged from 0.173 to 0.844 with average allele frequency of 4.91. Fourteen (14) primer pairs were polymorphic to identification of genotype linked to CBSD resistance total of 63 alleles with average of 4.5 alleles per locus. These markers will be useful for application in genetic conservation and plant breeding. The genetic diversity observed by dendrogram revealed four major clusters and one sub clusters, varieties most closely related were Per 458 and Mex 55 (D=0.1732), TME 1389, and TME 1368 (D=0.1982), Mkita and Kalolo (D=0.3981) followed by Pesangani and Kigoma (0.4912) while distantly related genotype were these varieties BRA 990 and Mcx 55 (0.7089). Albert and Mkita (0.6036), BRA255 and Cubl (0.6054), TME 230 and TME 539 (D=0.59I4), and Namikonga and Albert (0.5139).enGenetic studiesExpressed simple sequence repeat (ESSR)Cassava cropCassava brown streak disease resistanceThesis