Close relatedness between ‘Kenroku’ and ‘Annou-imo’ sweet potato cultivars

Abstract

Sweet potato ‘Kenroku’ is a palatable orange-fleshed cultivar, which was selected by Ishikawa Agricultural Experimental Station in the 1930’s. Because morphology of the shoot and storage root of ‘Kenroku’ resembled those of the so-called ‘Annou-imo’, we compared ‘Kenroku’ with five ‘Annou-imo’ landraces and cultivars. Morphology of mature leaves was indistinguishable among ‘Kenroku’, ‘Annou 3’, ‘Annou-imo 4’, ‘Annou-beni’, and ‘Annou-kogane’; their immature tip-leaves were purple and contained anthocyanins. Skin of the storage root was red in ‘Kenroku’, ‘Annou 3’, and ‘Annou-beni’, and white in ‘Annou-imo 4’ and ‘Annou-kogane’; all of them contained β-carotene in their flesh. The above characteristics of the leaf and storage root of ‘Annou-imo 1’ differed considerably from those of ‘Kenroku’ and the four ‘Annou-imo’ landraces and cultivars described above. Cleaved amplified polymorphic sequence analysis with 27 polymorphic marker fragments distinguished ‘Kenroku’ from ‘Izumi 13’ or ‘Kurimasari’ (progenies of crosses with ‘Kenroku’), but it could not distinguish ‘Kenroku’ from ‘Annou 3’, ‘Annou-imo 4’, ‘Annou-beni’, or ‘Annou-kogane’. Random amplified polymorphic DNA analysis with 45 polymorphic marker fragments distinguished ‘Kenroku’ from ‘Izumi 13’, ‘Kurimasari’, Annou-imo 4’, and ‘Annou-kogane’, but not from ‘Annou 3’ or ‘Annou-beni’. Because ‘Annou-imo’ landraces including ‘Annou 3’ were collected in Tanegashima for some time after World War II, and the cultivar ‘Annou-beni’ was selected from ‘Annou 3’, the above results strongly indicate that ‘Annou-imo’ landraces in Tanegashima originate from ‘Kenroku’, which spread throughout Japan just after World War II.