Studies on Molecular Genetic Diversity and Useful Genomic Traits of Yam (Dioscorea Spp) Germplasm Collections From Ethiopia
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Date
2014-06
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Addis Ababa University
Abstract
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.
Key Words: Ethiopia; Dioscorea species; Morphology; Proximate Composition;
Mineral Contents; Simple Sequence Repeats (SSR)
Description
Keywords
Ethiopia; Dioscorea species; Morphology; Proximate Composition; Mineral Contents; Simple Sequence Repeats (SSR)