GENE LIMITING CADMIUM ACCUMULATION IN RICE

DOI: 10.1073/pnas.1005396107
Journal: Proceedings of National Academy of Sciences of the United States of America
Year of Publication: 2010
Volume: 107
Issue: 38
Authors: Daisei UenoaNaoki YamajiaIzumi KonobChao Feng HuangaTsuyu AndobMasahiro Yanoc, and Jian Feng Ma

Abstruct

Intake of toxic cadmium (Cd) from rice caused Itai-itai disease in the past and it is still a threat for human health. Therefore, control of the accumulation of Cd from soil is an important food-safety issue, but the molecular mechanism for the control is unknown. Herein, we report a gene (OsHMA3) responsible for low Cd accumulation in rice that was isolated from a mapping population derived from a cross between a high and low Cd-accumulating cultivar. The gene encodes a transporter belonging to the P1B-type ATPase family, but shares low similarity with other members. Heterologous expression in yeast showed that the transporter from the low-Cd cultivar is functional, but the transporter from the high-Cd cultivar had lost its function, probably because of the single amino acid mutation. The transporter is mainly expressed in the tonoplast of root cells at a similar level in both the low and high Cd-accumulating cultivars. Overexpression of the functional gene from the low Cd-accumulating cultivar selectively decreased accumulation of Cd, but not other micronutrients in the grain. Our results indicated that OsHMA3 from the low Cd-accumulating cultivar limits translocation of Cd from the roots to the above-ground tissues by selectively sequestrating Cd into the root vacuoles.

Keyword:
Itai-itai disease