Breeding and characterization of the rice (Oryza sativa L.) line “Akita 110” for cadmium phytoremediation

Cadmium (Cd) is a heavy metal that is toxic to humans, and the accumulation of Cd in rice (Oryza sativa L.) grains is a widespread problem in rice agriculture. Phytoremediation is one of the most effective methods for reducing soil Cd levels in paddy fields, and rice is a promising candidate for phytoremediation. In this study, we developed the rice line Akita 110 for use in Cd phytoremediation, particularly in Akita Prefecture, Japan. Akita 110 was derived from a cross between Cho-ko-koku and Akita 63. Compared to Akitakomachi, which is the leading cultivar in Akita Prefecture, Japan, Akita 110 exhibited a heading date and maturing date that were 16 and 15d later, respectively. The culm length of Akita 110 was remarkably shorter than that of Cho-ko-koku, and Akita 110 exhibited improved lodging resistance. The shoot dry weight of Akita 110 was larger than that of Cho-ko-koku. Akita 110 exhibited a non-shattering phenotype. The Cd extraction of Akita 110 was equivalent to that of Cho-ko-koku. The average of Cd extraction using Akita 110 in five different Cd-contaminated fields was 20.1mgm(-2), whereas that using Cho-ko-koku was 24.3mgm(-2). In a large-scale field trial, Cd levels in shoots of Akita 110 were equivalent to those of Cho-ko-koku. One year from initial planting, soil Cd concentrations in plots remediated with Akita 110 reduced by 15.5%, whereas remediation with Cho-ko-koku reduced soil Cd levels by 10.1%. The Akita 110 developed here exhibits improved cultivation traits compared to the Cho-ko-koku, with comparable Cd extraction performance. Thus, Akita 110 is a promising candidate for Cd phytoremediation in northern parts of Japan.