High levels of genetic diversity in Salix viminalis of the Czech Republic as revealed by microsatellite markers

Willows (Salix spp.) grown as short rotation coppice are recognised as an important bioenergy crop, and breeding programmes are underway in several countries, including the Czech Republic. The basket willow Salix viminalis is one of the few willow species that is widespread in the Czech Republic and thus a potential source of diversity, but the most extensive germplasm collection available shows evidence of redundancy. To investigate levels of variation in natural populations of this species for use in crop improvement programmes, a set of 38 microsatellite markers was used to assess genetic diversity and population structure among 84 S. viminalis individuals collected from seven Czech rivers (the Odra, Bečva, Morava, Dyje, Jihlava, Sázava and Vltava), covering a wide geographic distribution. The markers detected 6.95 alleles per locus on average with 92 % of the sampled individuals having a unique multilocus genotype giving a high clonal richness measure among all samples (R = 0.952). Three sets of putative clones (with identical genotypes as determined by the markers used here) were also identified. Significant levels of genetic diversity were revealed within all sampling sites. With the exception of sites on the Odra and Morava, pairwise F ST (0.02–0.1) values indicated moderate differentiation between sites. Principal coordinates analysis revealed some separation of the Dyje individuals from all others. This was in agreement with the population structure results derived from Bayesian analyses using STRUCTURE software. These results provide the first evidence that potentially useful levels of genotypic variation are present within natural S. viminalis populations in the Czech Republic.