Genetic diversity in fruiting and flower-ornamental Japanese apricot (Prunus mume) germplasms assessed by SSR markers

The genetic diversity and relationships among 127 Japanese apricot (Prunus mume Siebold et Zucc.) germplasms, including 56 fruiting and 55 flower-ornamental cultivars derived from Japan, 8 germplasms from China, 7 germplasms from Taiwan and 1 germplasm from Thailand were assessed by SSR markers. Thirty-nine out of 58 SSR markers developed from peach and apricot could produce one or two amplified fragments in Japanese apricot, suggesting transferability across species. Fourteen SSR markers showing clear amplification and high polymorphisms were chosen for further analysis. A total of 155 putative alleles were observed in Japanese apricot for 14 SSR loci with an average value of 11.1. The values of observed heterozygosity (HO) and expected heterozygosity (HE) ranged from 0.29 to 0.88 (mean value of 0.61) and 0.32 to 0.92 (mean value of 0.68), respectively. A phenogram for 127 Japanese apricot and 3 apricot germplasms showed 3 major clusters, 1) Bungo group of Japanese apricot and apricot, 2) germplasms from Taiwan and Thailand, 3) fruiting and flower-ornamental germplasms derived from Japan and China. In the present study, definite genetic differences were not found between fruiting and flower-ornamental groups, which supported the hypothesis that fruiting cultivars have been selected from flower-ornamentals.