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

Abstract

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 15 d 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 20.1 mg m−2, whereas that using “Cho-ko-koku” was 24.3 mg m−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.