Breeding and characterization of the high cadmium-accumulating rice line ‘Akita 119’

Cadmium (Cd) is a toxic heavy metal that is mainly accumulated through the consumption of foods produced in Cd-contaminated fields. Phytoremediation is one of the most effective methods to reduce the soil Cd concentration. In this study, we bred a new rice line, ‘Akita 119’, for Cd phytoremediation. ‘Akita 119’ was obtained by a soft X-ray mutation of ‘Cho-ko-koku’, a naturally high-Cd-accumulating rice cultivar. The heading date of ‘Akita 119’ was about 2 weeks later than that of ‘Akitakomachi’, which is the leading cultivar in Akita Prefecture, Japan. ‘Akita 119’ has a short culm length and many panicles. The shattering resistance and lodging resistance of ‘Akita 119’ were improved compared to ‘Cho-ko-koku’. The thousand-grain weight of ‘Akita 119’ was much smaller than that of ‘Akitakomachi’, and grains of ‘Akita 119’ could be easily distinguished from general japonica cultivars. When ‘Akita 119’ was grown in Cd-contaminated fields, the shoot dry weight and Cd concentration were similar to those of ‘Cho-ko-koku’. These results demonstrate that ‘Akita 119’ has improved agronomic characteristics compared to ‘Cho-ko-koku’ while retaining the ability to extract Cd. Therefore, it should be considered a promising candidate for Cd phytoremediation in paddy fields in northern parts of Japan.