Rapd Analysis for Genetic Diversity and Relationships in Tetraploid Wheats (Aabb Genome) of Ethiopia
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Date
2005-02
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Addis Ababa University
Abstract
Twenty-five tetraploid wheat landraces and 15 improved durum cultivars were used to study
the diversity and relationships within and among tetraploid species and regions of origin, and
improved cultivars. Thirty-one polymorphic bands produced by two RAPD marker primers
were used for the analysis. The mean Shannon diversity index (H) for landrace collections and
improved cultivars were 0.34 and 0.23, respectively. Among the four species studied, T.
durum was with the highest (0.32) diversity value whereas T. polonicum with the lowest
(0.26). Similarly, Wello region collections revealed highest (0.27) tetraploid wheat diversity
while Shewa collections, the lowest (0.22). The within species and regions variations were
81.4% and 72.2%, respectively. It suggests the need to collect more wheat germplasm
samples within regions. Cluster analysis for all genotypes grouped mainly into landrace
collections and improved cultivars. Clustering of landrace genotypes resulted in four groups
mainly according to their regions of origin. However, it failed to group on the basis of their
species. It suggests the presence of more genetic differentiation among regions than species.
The lowest (0.00) and highest (0.73) genetic distances were observed between Wet1224 and
Wet1570, and Wet1650 and Bae1117, respectively. The between species genetic distance was
lowest (0.016) between T. polonicum and T. turgidum, but highest (0.051) between T.
aethiopicum and T. durum. Clustering of improved durum cultivars formed four groups at
80% similarity coefficient. The lowest genetic distance (0.032) was observed between
cultivars Ld357 and Boohai, Foka and Kilinto, and Tob66 and DZ 1640. The highest distance
(0.34) was between Asassa and Bichena, Asassa and Boohai, and Bichena and Ude cultivars.
The average distance within improved durum cultivars was 0.157. It indicates that all the 15
improved cultivars are relatively similar. Little correlation was observed between groups
formed by cultivars and common parentage.
positive for M. bovis. The results indicated that M. tuberculosis is the causative
species for tuberculous lymphadenitis in Dera.