Genetic Diversity Assessment of Yams (Dioscorea Spp.) From Ethiopia Using Inter Simple Sequence Repeat (Issr) Markers
No Thumbnail Available
Date
2015-04-04
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The genetic diversity and relationships of 70 accessions of yam belonging to Dioscorea
cayenensis/Dioscorea rotundata complex (55), Dioscorea bulbifera (13) and Dioscorea
alata (2 as a reference) were assessed using six ISSR primers. DNA was extracted from a
bulk of two plants per accession using a modified CTAB method. Six ISSR primers
amplified 77 fragments with 75 (97.40%) polymorphism at genus level. The genetic
diversity, estimated by Gene diversity and Shannon’s index were 0.36 and 0.53,
respectively, revealing a high level of genetic variation at genus level. At species level 75
bands were amplified for D. cayenensis/D. rotundata complex, out of which 71 were
polymorphic accounting for 92.2% polymorphism. Gene diversity and Shannon's index for
D. cayenensis/D. rotundata complex were 0.33 and 0.49, respectively. In case of D.
bulbifera a total of 64 bands were scored, out of which 55 were found to be polymorphic
which resulted in 71.4% polymorphism. Gene diversity and Shannon's index for this
species were 0.24 and 0.47, respectively. Genetic diversity analysis of D. cayenensis/D.
rotundata complex accessions showed that Gedeo were the most diverse among
populations and South among groups. Analysis of molecular variance (AMOVA) indicated
the presence of higher proportion of variation within species (63.9%) than among species
(36.1%) which could be due to presence of several shared bands. AMOVA for D.
cayenensis/D. rotundata complex also showed higher within population variation (53.6)
than among populations (46.4). This could be due to gene flow through seed materials
exchange among local farmers. Cluster analysis showed grouping of most of the accessions
according to their species. In addition, cluster analysis for relationship between D.
cayenensis/D. rotundata complex accessions showed grouping of some of the accessions
according to their population but it failed to produce clear species boundary between D.
cayenensis/D. rotundata complex. The results suggested that there exists a high level of
genetic diversity in yams of Ethiopia to be exploited for future improvement (breeding) of
the crop.
Description
Keywords
D. Bulbifera, D. Cayenensis/D, Rotundata Complex, Genetic Diversity, Yam