Genetic Diversity of Persian Walnut Revealed by a Set of Microsatellite Markers in Indiana

Fourteen microsatellite markers of black walnut were developed and evaluated in a Persian walnut genotypes and cultivars. Those primers were used for studying diversity in 48 Persian walnut genotypes/cultivars belonging to four different geographical groups, such as Indiana, California, Eastern Europe, and few sample from Russia. All of the markers were polymorphic and revealed a total of 50 alleles ranging from 4 to 8 alleles per locus with a mean value of 6 alleles per locus. No relation could have been observed between any loci and cold hardy resistant genotype. Cold hardy resistant cultivars and genotypes did not separate on the dendrogram obtained by cluster analysis. Indiana and California cultivars formed separate groups while other genotypes formed smaller sub-groups or scattered among different groups. The size of allele was presented for each sample that allowed the easy observation of allele frequencies in each geographical group at each locus. Using this information, dissimilarities and similarities between cultivar groups can be easily estimated. The analysis revealed the links between the American and European walnut genotypes and confirmed that the Russian and Eastern European genotypes are related.