Genetic Diversity and Population Structure of Ethiopian Barley [Hordeum vulgare (L.)] germplasm Using Inter Simple Sequence Repeat (ISSR) Markers

Abstract

Barley is a member of the grass family Poaceae (Gramineae), specifically the Triticeae tribe). The Triticeae tribe includes 350 species and several economically significant cereals and forages. The present study was designed to investigate the genetic diversity and population structure of 97 barley germplasms in Ethiopia representing 14 populations using 8 ISSR markers. To analyses the genetic diversity in subdivided populations, the total genetic diversity (Ht), intrapopulation genetic diversity (Hs) and gene differentiation (Gst) were determined. The POPGEN 32 software was used to measure the following parameters: observed number of alleles (na), effective number of alleles (ne), Nei’s gene diversity (h), percentage of polymorphic loci (PPL) and Shannon’s information index (I). A genetic dissimilarity matrix parameter was calculated using Mega software version 2.3.4. Population structure and admixture patterns were determined using the admixture model based on the Bayesian algorithm implemented in STRUCTURE software version 2.3.3). The admixture model with correlated allele frequencies was used, assuming that the genome of each individual resulted from the mixture of K ancestral populations. All the markers used in the present study shows polymorphic and less to moderate informative. The genetic diversity index (h) for all primers ranged from 0.119 to 0.373 and average mean value of 0.193 alleles per locus. Polymorphic information content ranged from 0.127 to 0.263 with overall mean of 0.178 and within-populations genetic diversity was confirmed with gene diversity values ranging from 0.28 to 0.43 with an overall mean of 0.36. Analysis of molecular variance revealed that most (63%) of the total genetic variation was accounted for within populations genetic variation and 37% was among population variation. Clustering and principal Co-ordinate analyses were sharply grouped the samples based on their genetic structure. Population structure analysis revealed the presence of four sub-populations with higher degree of genetic admixture. Among the studied populations, Jimma and Arsi populations showed relatively higher gene diversity than others indicating these sites could be targeted for breeding and conservation of barley. Therefore, the present study had successfully provided the genetic diversity and population structure of barley germplasms in the studied areas.