Kentaro Yasuda

RAPD variation in wild, weedy and cultivated azuki beans in Asia.

RAPD (Random Amplified Polymorphic DNA) variation was assessed in 42 accessions of azuki bean (Vigna angularis) including wild, weedy and cultivated races and in three accessions of two related species used as outgroups. A much lower level of genetic variation was observed in cultivated and weedy azuki beans compared to wild azuki bean. Wild azuki bean (V. angularis var. nipponensis) has relatively high genetic variation in subtropical highlands of Asia compared to the Far East. Although cultivated azuki bean has low RAPD variation, accessions from subtropical highlands and Southeast Asia showed different RAPD features compared to those of the Far East. It is hypothesized that the cultivated azuki bean has been derived from wild azuki bean in the Far East; the high variation in wild azuki bean has been created through its natural dissemination; and the relatively low variation in cultivated azuki bean has come about through human dissemination after genetic bottleneck reduced by domestication. In addition, high genetic diversity in wild azuki bean in subtropical highlands of Asia is regarded as an important genetic resource in azuki improvement.

A Test for Molecular Identification of Japanese Archaeological Beans and Phylogenetic Relationship of Wild and Cultivated Species of Subgenus Ceratotropis (Genus Vigna, Papilionaceae) Using Sequence Variation in Two Non-coding Regions of the trnL and trnF Genes

Phylogenetic relationships were analyzed in nine species belonging to subgenus Ceratotropis (genus Vigna, Papilionaceae), including cultivated, weedy and wild races of azuki bean (V. angularis), and five outgroup species by sequences in the trnL intron and trnL-F intergenic spacer of cpDNA, in order to perform molecular identification of archaeological beans in Japan. The modern species of subgenus Ceratotropis had similar sequences in the two non-coding regions ranging from 952 bp to 1027 bp with 36 substitutions and 6 indels. The strict consensus phylogenetic tree confirmed the monophyly of the Ceratotropis and two subordinate groups: the azuki bean group and the mung bean group. The azuki bean group was comprised of three races of azuki bean, rice bean (V. umbellata), V. nakashimae and V. minima var. minor. The mung bean group was comprised of mung bean (V. radiata), blackgram (V. mungo), moth bean (V. aconitifolia), V. trilobata and V. reflexo-pilosa. All accessions of V. angularis, including cultivated, weedy and wild azuki beans, shared the same sequence with a specific deletion of 51 bp. Since this deletion was confirmed in the archaeological beans excavated from the ruins during the Yayoi (ca. 2300 yrb.p.), Satsumon (650 yr b.p.), and Edo (155 yr b.p.) periods of Japan, it is suggested here that the azuki bean has long been utilized in Japan.