The genetic relationship of mume cultivars was resolved by random amplified polymorphic DNA (RAPD) assay using 95 decamer oligonucleotide primers. The heterozygosity within Prunus mume was confirmed by the numerous polymorphism of DNA fingerprints which exsist among cultivars.
Representative cultivars were selected from four groups; 1) Ko-ume (small fruit), 2) Chuu-ume (medium fruit), 3) Ou-ume (large fruit), 4) hybrid between mume and apricot; which were generally classified by fruit size and morphological traits. Japanese mume cultivar were developed independently as indicated by the dissimilarity index between Taiwan and Japanese mume. The Ko-ume and Taiwan mume group with its narrow genetic variation are different from 'Bungo' which has characteristics of the apricot. Thus, they are genetically distant from 'Bungo' and apricot.
Four flowering mume cultivars in this experiment are closely related to the fruiting mume but were classified into a segregate group, because a possibility exists that the fruiting mume may be a derivative of the flowering ones.
The 3 groups of mume cultivars : 1) 'Muroya', 'Inazumi', and 'Tounoume'; 2) 'Komukai' and 'Gojirou'; and 3) 'Suzukishiro' and 'Taihei' consists of synonyms. Therefore, they could not be distinguished from each other with precise RAPD assay capable of detecting DNA polymorphisms. The possibility seems to be high that the cultivars within the 3 groups are identical. 'Takadaume' was shown as the nearest to apricot among mume cultivars. 'AM2-1', 'AM2-2' and 'AM2-4' which are artificial hybrids between 'Jizouume' and 'Heiwa' were classified into the same cluster as 'Bungo'. It is sufficient evidence to prove that 'Bungo' is a hybrid between mume and apricot. It seems reasonable to suppose that RAPD assay has the potentiality to identify mume cultivars, considering the capability of discriminating these artificial hybrids.
In conclusion, mume cultivars can be classified into seven groups; 1) Taiwan mume, 2) Ko-ume (small fruit), 3) Chuu-ume (medium fruit), 4) Ou-ume (large fruit) with white flower, 5) Ou-ume (large fruit) with pink flower, 6) Anzu-ume or Bungo-ume (apricot-mume hybrid), 7) Sumomo-ume (plum-mume hybrid). The DNA fingerprints of mume genome generated by RAPD assay reflect the own origin of mume cultivars. Hence, the method is expected to contribute to a mume breeding project.
Japanese Society for Horticultural Science