AFLP identification of Berberis thunbergii cultivars, inter-specific hybrids, and their parental species

Cultivars of Berberis thunbergii DC. are among the most popular garden shrubs in the United States. Using 174 amplified fragment length polymorphism (AFLP) markers we were able to differentiate between 43 B. thunbergii cultivars and analyse the genetic similarity of 62 B. thunbergii genotypes, B. julianae, B. koreana, B. vulgaris and B. vulgaris ‘Atropurpurea’. Seven different accessions of B. thunbergii ‘Crimson Pygmy ’ from a variety of sources had identical AFLP profiles, indicating that there is only one genotype in cultivation and not a collection of similar genotypes. B. thunbergii cultivars ‘Crimson Pygmy’, ‘Crimson Dwarf’, and ‘Monomb ’ Cherry Bomb ™ could not be distinguished and appeared to be the same genotype. The B. thunbergii cultivars ‘Concorde ’ and ‘Criruzam ’ Crimson Ruby ™ are most likely genotypes of B. ottawensis since they formed a cluster with known B. ottawensis cultivars. The B. thunbergii var. atropurpurea accessions analysed had Jaccard’s coefficients ranging from 0.89 – 0.99 and, therefore, were probably derived from highly inbred seed. A dichotomous identification key was developed for 42 B. thunbergii cultivars and hybrids and B. vulgaris ‘Atropurpurea ’ using 23 markers.This key can be used to ensure that only legal cultivars are sold, if cultivar-specific bans are enacted, and to prevent the importation of rust-susceptible cultivars into Canada. Ornamental cultivars of Japanese barberry (Berberisthunbergii DC.) are among the most popular garden shrubs in the United States due to their hardiness, ease o