A retrospective analysis of spring barley germplasm development from 'foundation genotypes' to currently successful cultivars

Twenty-eight mapped barley SSRs were used to examine changes in the level a nd pattern of variability in northern European spring barley over time. Com paring the most recently introduced cultivars with a group of 19 landraces and key progenitors termed 'foundation genotypes' we observed a reduction i n the spectrum of alleles at 28 loci over time, and highlighted chromosomal regions with limited SSR allelic variation. The 19 'foundation genotypes' contained 72% of the alleles present in all the cultivars sampled. The smal lest number of genotypes required to encompass all of the alleles detected in this study was 44, several of which were recently introduced cultivars. The level of diversity within modern cultivars was lower (0.484) than in th e 'foundation genotypes' (0.597), although the values varied with the SSR l ocus. A total of 74 rare alleles (frequency <0.05) were detected in the cul tivar sample, representing 34% of the total. Measures of genetic distance u sing SSRs, kinship coefficients and botanical descriptors were compared. Al though the correlations between SSRs and kinship and SSRs and botanical des criptors were statistically significant (r = 0.26, p < 0.001 and r = 0.09, p < 0.001, respectively), SSR analysis provided greater resolution and allo wed better discrimination between genotypes. Discussion of the results focu ses on how this information can provide new opportunities in barley breedin g.