Genetic diversity of ten black walnut (Juglans nigra L.) cultivars and construction of a mapping population

Black walnut (Juglans nigra L.) nut production stands on the brink of potentially great market expansion that can only be realized with significant genetic and horticultural improvement, such that commercial production becomes feasible. The goal of this study was to incorporate microsatellite/simple sequence repeat (SSR) markers to genotype 11 cultivars and selections, and establish a mapping population from a cross of two cultivars, “Football” × “Sparrow.” Morphology of these two cultivars coupled with phylogenetic analysis supports the notion that a cross between them may yield desirable hybrids. Of the 51 SSR markers amplified, 23 were polymorphic and useful for genotyping. A selection mislabeled as “Mintyle” was definitively identified as “Mintle”; therefore, the number of cultivars was reduced to 10. Furthermore, seven of the 23 markers were used to identify 91 intraspecific hybrids (“Football” × “Sparrow”) resulting from open pollination, thereby establishing the first mapping population of black walnut using SSR markers.