A common-garden evaluation of geographically diverse American elderberry genotypes selected for varying polyphenol profiles

Abstract American elderberry ( Sambucus nigra subsp. canadensis ) is an increasingly popular specialty crop, primarily grown in North America for use of flowers and fruits in dietary supplements and foods. Elderberry is a versatile shrubby species, with excellent utility in a variety of agroforestry systems, and provides important ecosystem services. Little is known about the genetic diversity of American elderberry, especially in terms of horticultural attributes and beneficial metabolites. A previous project sampled wild germplasm from the eastern and midwestern United States. Fruit from these samples was analyzed for polyphenol profiles, after which propagules of accessions of interest were collected for further study. Eighteen geographically diverse accessions, along with three standard cultivars, were brought into replicated, randomized, common-garden plantings in southwest Missouri, USA. The objective was to assess genetic diversity, breeding potential, and genetic and environmental influences on polyphenol profiles. Horticultural data were quantified across four years, and fruit samples were analyzed for polyphenol profile over two years. Most horticultural parameters varied significantly across factors of genotype, site, and year. Among genotypes, budbreak varied 32 days and peak flowering ranged 21 days. Plant height also showed considerable variation among genotypes, ranging from 0.96–1.84 m. Noting that the accessions were selected for phytochemical diversity rather than horticultural potential, fruit yields ranged from 0.72–5.88 kg/plot (plot = 2.23 m 2 , containing two plants). Among five anthocyanins and seven flavonols / phenylpropanoids quantified, statistical differences in metabolite production were found among genotypes in all cases. This snapshot of the genetic diversity among horticultural and metabolomic factors within American elderberry underscores the potential for breeders to select various traits of interest as the crop continues to develop.