Studies On Molecular Genetic Diversity And Useful Genomic Traits Of Yam (dioscorea Spp) Germplasm Collections From Ethiopia

Yam (Dioscorea spp L.) is one of the underutilized tuber crops in Ethiopia. It isrncultivated mainly in South and Southwestern part of the country. Sixty yam accessionsrn(Based on availability 6-15 sprouted tubers of each sample) from ten different geographicrnorigins of Southern Nations Nationalities & People’s Regional State and Oromiya regionrnof the country were used in this study. The sprouted tubers of some accessions werernreceived from Research Centers where others were directly collected from farmers’ fieldsrnduring early March, 2010. These collected yam genotypes were planted in two differentrnexperimental sites at Hawasa and Wonago.rnUnder morphological variability study the collected yam (Dioscorea spp) were identifiedrnin to six different Dioscorea species. These were D. bulbifera L., D. abyssinica Hochst.,rnD. cayenensis Lam., D. rotundata Poir , D. praehensilis Benth. and D. alata L. Thesernidentified Dioscorea species were subjected to morphological characterization study tornobserve their diversity relatedness among and within the genotypes by observing onlyrnone type of species from a plot. Based on Shan UPGMA cluster analysis, all sixty yamrngenotypes included in the study were grouped in to five clusters. In this analysis therncophenetic correlation coefficient r=80 revealed the efficiency of the dendrogram.rnForty two different acessions of six different species of yam tubers D. bulbifera,rnD. abyssinica, D.cayenensis, D.rotundata D. praehensilis, and D. alata from six differentrnmajor growing regions of the country Gedio, Gamogofa, Wolita, Dauro, Wolega andrnJima were selected randomely for nutritional analysis from the expermental field wherernyam morphological diversity was studied. The result from this study showed that yam isrnthe potential tuber crop with respect to both proximate composition and mineral contents.rnIn the present study, different Dioscorea species were observed within most yamrnaccession found in same vernacular name. Hence, a total of two hundred and fifty eightrnyam leaf samples from six different Dioscorea species (one to five yam plants fromrnexperiemental plot) were observed separetly using twenty SSR loci. Among these, twornhundred and ten yam landraces were taken independently to each species and regionrnbased statistical analysis from twelve SSR loci which showed clear electrophoretic bands.rnDistance matrix derived un-rooted Phylogram of 210 accessions based on six Dioscorearnspecies indicated the separation of D. cayenensis, D. abyssinica and D. bulbifera byrngrouping them in to four different clusters. One cluster group separated the Dioscorearnspecies (D. praehensilis and D. abyssinica) from those of cultivated species. Similarlyrntwo clusters grouped D. praehensilis and D.rotundata together whereas two sub clusterrngroups were composed of sixty four yam acessions overlapped five species together byrnexcluding D.cayenensis. A similarity matrix derived UPGMA cluster analysis based onrngeographical sites showed nine distinct clustering groups which indicated presence ofrnrelationship between genetic distances to that of geographical distance in most ofrnclustering groups. These cluster grouping is supported by Analysis of Molecular Variancern(AMOVA) which showed the significance genetic variation of 210 yam accessionsrnwithin and among ten collection sites . Combined data analysis was also made for 42 yam accessions which have commonrnnutritional, morphological and microsatellites data set. The dendrogram obtained basedrnon combined analysis grouped four different yam (Dioscorea spp) from differentrngeographic origins separately within five clusters. Generally SSR markers were powerfulrnto demonstrate diversity of Ethiopian yam (Dioscorea spp) with respect to their speciesrngroups and geographic location. The Result of morphological, nutritional compositionrnand combination of all data set analysis gave some results in agreement with result ofrnSSR marker. Therefore, such type of study is vital to drag out different type ofrninformation and helps to enhance productivity of the crop in different aspects.rnKey Words: Ethiopia; Dioscorea species; Morphology; Proximate Composition;rnMineral Contents; Simple Sequence Repeats (SSR)

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