Bekele Endashaw (Professor)Girma Gezahegn2018-06-292023-11-092018-06-292023-11-092007-07http://etd.aau.edu.et/handle/123456789/5146Three wild rice populations of Ethiopia (one from Gambella and two from Gonder) and three cultivated rice populations (O. sativa from Gonder, O. glaberrima from West Africa and NERICA rice (NERICA-3; cultivar developed through interspecific hybridization between O. sativa and O. glaberrima), from Gonder) were studied. Inter simple sequence repeats (ISSRs) as a molecular marker was used to assess genetic diversity both within and between species using six ISSR primers, where four of them were dinucleotides and two tetranucleotides primers. A total of 93 clear and reproducible bands were amplified from the six ISSR primers. Both UPGMA and neighbor joining trees were constructed for each individual and population using Jaccard’s similarity coefficient of ‘0’ absent and ‘1’ present data. The trees clearly indicated six distinct groups which are based on populations of origin. The PCO analysis also recovered the UPGMA and neighbor joining trees groups, although wild Gonder-1 intermixed with wild Gonder-2. O .glaberrima, O. sativa and NERICA-3 clustered as a major group while O. barthii and O. longistaminata were clustered as the second major group. Such clustering of O. glaberrima with O. sativa and NERICA-3 is considered to be due to genetic admixture of O. glaberrima with O. sativa. The genetic diversity result generally indicated that wild rice populations were found to have higher gene diversity (0.14) than cultivated rice populations. The over all gene diversity and percent polymorphisms were found to be higher in wild rice than in cultivars (0.11). The Shannon’s diversity index also confirmed the existence of higher diversity in wild rice populations of Ethiopia than cultivated species used in the present study. Furthermore, partitioning of the Shannon’s diversity showed that the majority of the variations were observed among population (63%). Similarly, AMOVA demonstrate highly significant (P=0.00) genetic differences among populations within groups, among groups (cultivated and wild) and within populations. Of the total variation, 49.4% was attributable to among populations within groups, 26.4% to among groups and the least, 24.2% to within populations. Key words: genetic diversity, wild rice populations, cultivated rice, Oryza sativa, Oryza glaberrima, NERICA, ISSRengenetic diversitywild rice populationscultivated riceOryza sativaOryza glaberrimaNERICAISSRThesis