Chloroplast DNA microsatellite analysis supports a polyphyletic origin for barley

Five barley chloroplast DNA microsatellites (cpSSRs) were used to study genetic relationships among a set of 186 barley accessions - 34 Hordeum vulgare ssp. spontaneum (HS accessions) from Morocco, Ethiopia, Cyprus, Crete, Libya, Iraq, Iran, Turkey, Afghanistan and Israel, 122 H. vulgare ssp. vulgare landraces (HV landraces) from Spain, Bolivia (old Spanish introductions), Morocco, Libya and Ethiopia and 20 modern European spring barleys (HV cultivars). All loci were polymorphic in the material studied, with the number of alleles per locus ranging from two to three. Fifteen multi-locus haplotypes were observed, 11 in HS accessions and seven in HV landraces and cultivars. Of the seven haplotypes found in the HV lines, three were shared with the HS accessions, and four were unique. Cluster analysis revealed two main groups, one consisting of HS accessions from Ethiopia and the HV landraces from Spain, Bolivia (old Spanish), Morocco and Ethiopia, whereas the other larger group contained all of the other accessions studied. Based on these grouping and the existence of haplotypes found in the HV landraces and cultivars but not in the HS wild barley, a polyphyletic origin is proposed for barley, with further centres of origin in Ethiopia and the Western Mediterranean.