Analysis of Ploidy, Genetic Diversity and Speciation of the Genus Aronia

Aronia is an ornamental genus with white spring flowers, red or black fruit, orange-red fall color and easy culture. Black fruited Aronia is also increasingly grown as a nutraceutical fruit crop. Great potential exists to improve ornamental and fruiting Aronia germplasm through breeding. Wild Aronia genotypes from across the native range were collected and subjected to flow cytometry and amplified fragment length polymorphism (AFLP) analysis to better understand ploidy, genetic relatedness of accessions and speciation within the genus. Eight primer combinations used generated a total of 667 fragments of which 77.8% were polymorphic. Jaccard’s similarity coefficient among accessions ranged from 0.42 to 1. Cluster analysis of the AFLP data using unweigthed pair group method with arithmetic mean (UPGMA) grouped accessions into different taxonomic groups including mitschurinii, prunifolia, arbutifolia, diploid melanocarpa, tetraploid melanocarpa, and a distinct group of tetraploid melanocarpa accessions from the southern extreme of its range.These southern, black fruited, glabrous genotypes may represent a new species of Aronia. Diploid melanocarpa accessions were all from New England states, while melanocarpa found outside of New England were all tetraploid and mostly originating from states bordering the Great Lakes. Arbutifolia and prunifolia accessions were tetraploid. A single triploid prunifolia and melanocarpa accession were also identified. The large-fruited, large-leaved accessions, typical of those used in commercial fruit production, all grouped as mitshurinii, further confirming the intergeneric hybrid nature of this taxa and the need to separate it from melanocarpa taxonomically.