Efficient mutation induction using heavy-ion beam irradiation and simple genomic screening with random primers in taro (Colocasia esculenta L. Schott)

Progress in conventional breeding methods for taro (Colocasia esculenta L. Schott) via crossing has been limited, and suitable genetic materials for the development of new cultivars are scarce as most commercial taro cultivars are either non-flowering or rarely flowering triploids. In an attempt to advance taro breeding, we performed mutational breeding by heavy-ion beam irradiation of multiple shoots of ‘Chiba maru’ cultivar. Using 2–10 Gy neon and carbon ion beams, we achieved a plant survival rate of more than 90 % and used 94 surviving plants for genomic screening. To efficiently detect DNA polymorphisms induced by ion beam irradiation in young plants, we used five sets of 15-mer randomly amplified polymorphic DNA and arbitrarily primed-polymerase chain reaction random primers based on retrotransposon sequences for genomic screening. Two plants had polymorphic DNA bands, and the specific DNA patterns were maintained in all leaves. In one of these plants, which lacked somatic mosaicism (Cm10), the polymorphic patterns were maintained in the leaves and cormels of clones propagated from daughter cormels. Ion beam irradiation of multiple taro shoots could thus generate mutants that can be developed as new cultivars; the resulting novel polymorphic patterns would facilitate inter- and intra-cultivar identification.