Studies on Molecular Genetic Diversity and Useful Genomic Traits of Yam (Dioscorea Spp) Germplasm Collections from Ethiopia

Atnafua, Bekele (2014) Studies on Molecular Genetic Diversity and Useful Genomic Traits of Yam (Dioscorea Spp) Germplasm Collections from Ethiopia. PhD thesis, Addis Ababa University.

[img] PDF (Studies on Molecular Genetic Diversity and Useful Genomic Traits of Yam (Dioscorea Spp) Germplasm Collections from Ethiopia)
Atnafua, Bekele.pdf - Accepted Version
Restricted to Repository staff only

Download (3MB) | Request a copy


Yam (Dioscorea spp L.) is one of the underutilized tuber crops in Ethiopia. It is cultivated mainly in South and Southwestern part of the country. Sixty yam accessions (Based on availability 6-15 sprouted tubers of each sample) from ten different geographic origins of Southern Nations Nationalities & People’s Regional State and Oromiya region of the country were used in this study. The sprouted tubers of some accessions were received from Research Centers where others were directly collected from farmers’ fields during early March, 2010. These collected yam genotypes were planted in two different experimental sites at Hawasa and Wonago. Under morphological variability study the collected yam (Dioscorea spp) were identified in to six different Dioscorea species. These were D. bulbifera L., D. abyssinica Hochst., D. cayenensis Lam., D. rotundata Poir , D. praehensilis Benth. and D. alata L. These identified Dioscorea species were subjected to morphological characterization study to observe their diversity relatedness among and within the genotypes by observing only one type of species from a plot. Based on Shan UPGMA cluster analysis, all sixty yam genotypes included in the study were grouped in to five clusters. In this analysis the cophenetic correlation coefficient r=80 revealed the efficiency of the dendrogram. Forty two different acessions of six different species of yam tubers D. bulbifera, D. abyssinica, D.cayenensis, D.rotundata D. praehensilis, and D. alata from six different major growing regions of the country Gedio, Gamogofa, Wolita, Dauro, Wolega and Jima were selected randomely for nutritional analysis from the expermental field where yam morphological diversity was studied. The result from this study showed that yam is the potential tuber crop with respect to both proximate composition and mineral contents. In the present study, different Dioscorea species were observed within most yam accession found in same vernacular name. Hence, a total of two hundred and fifty eight yam leaf samples from six different Dioscorea species (one to five yam plants from experiemental plot) were observed separetly using twenty SSR loci. Among these, two hundred and ten yam landraces were taken independently to each species and region based statistical analysis from twelve SSR loci which showed clear electrophoretic bands. Distance matrix derived un-rooted Phylogram of 210 accessions based on six Dioscorea species indicated the separation of D. cayenensis, D. abyssinica and D. bulbifera by grouping them in to four different clusters. One cluster group separated the Dioscorea species (D. praehensilis and D. abyssinica) from those of cultivated species. Similarly two clusters grouped D. praehensilis and D.rotundata together whereas two sub cluster groups were composed of sixty four yam acessions overlapped five species together by excluding D.cayenensis. A similarity matrix derived UPGMA cluster analysis based on geographical sites showed nine distinct clustering groups which indicated presence of relationship between genetic distances to that of geographical distance in most of clustering groups. These cluster grouping is supported by Analysis of Molecular Variance (AMOVA) which showed the significance genetic variation of 210 yam accessions within and among ten collection sites. Combined data analysis was also made for 42 yam accessions which have common nutritional, morphological and microsatellites data set. The dendrogram obtained based on combined analysis grouped four different yam (Dioscorea spp) from different geographic origins separately within five clusters. Generally SSR markers were powerful to demonstrate diversity of Ethiopian yam (Dioscorea spp) with respect to their species groups and geographic location. The Result of morphological, nutritional composition and combination of all data set analysis gave some results in agreement with result of SSR marker. Therefore, such type of study is vital to drag out different type of information and helps to enhance productivity of the crop in different aspects.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Ethiopia, Dioscorea species, Morphology, Proximate Composition, Mineral Contents, Simple Sequence Repeats (SSR)
Subjects: Q Science > Q Science (General)
Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
Q Science > QK Botany
Q Science > QR Microbiology
Divisions: Africana
Depositing User: Selom Ghislain
Date Deposited: 07 Sep 2018 06:49
Last Modified: 07 Sep 2018 06:49

Actions (login required)

View Item View Item