Genetic diversity and population structure of yam (Dioscorea spp.) from
western Ethiopia as revealed by simple sequence repeat markers
Abstract
This study examined Ethiopian yam genetic diversity and population
structure using SSR markers. Ten SSR markers were used to analyze a
total of 118 yam genotypes representing six population species that were
collected from four zones in western Ethiopia. A total of 92 alleles
with an overall mean of 9.2 per locus were detected. The average
expected heterozygosity (He) and allelic richness (AR) were 0.88 and
6.30, respectively. All SSR markers were polymorphic and highly
informative, with an overall mean polymorphic information content (PIC)
of 0.87. More ever, all SSR markers discriminated the variations among
the studied yam species. The overall mean expected heterozygosity (He)
and percentage of polymorphic loci within populations were 0.72 and
98.33, respectively. The highest genetic diversity indices were recorded
in the landrace yam populations of D. cayenensis, D. bulbifera, and D.
rotundata species. Analysis of molecular variance (AMOVA) revealed a
moderate but highly significant genetic differentiation (PhiPT=0.100, p
<0.0001). Most of the total genetic variation (91%) accounted
for the within-population variation, leaving only 9% for the
among-population genetic variation. STRUCTURE analysis based on the
Bayesian model weakly inferred two subgroups (K=2), confirming the high
potential of genetic admixtures and close relationships among the
studied yam genotypes, likely due to the presence of high gene flow (Nm=
2.39). D. alata landraces had the least genetic diversity, inferring the
need for strong conservation strategies. This study provided baseline
genetic diversity data for yam breeders to selectively breed for
desirable agronomic qualities and devise conservation measures.