Ion-beam irradiation, gene identification, and marker-assisted breeding in the development of low-cadmium rice

Satoru Ishikawa, Yasuhiro Ishimaru, Masato Igura, Masato Kuramata, Tadashi Abe, Takeshi Senoura, Yoshihiro Hase, Tomohito Arao, Naoko K. Nishizawa, Hiromi Nakanishi

Research output: Contribution to journalArticlepeer-review

251 Citations (Scopus)

Abstract

Rice (Oryza sativa L.) grain is amajor dietary source of cadmium(Cd), which is toxic to humans, but no practical technique exists to substantially reduce Cd contamination. Carbon ion-beamirradiation produced three rice mutants with <0.05 mg Cd·kg-1 in the grain compared with a mean of 1.73 mg Cd·kg-1 in the parent, Koshihikari. We identified the gene responsible for reduced Cd uptake and developed a strategy for marker-assisted selection of low-Cd cultivars. Sequence analysis revealed that these mutants have different mutations of the same gene (OsNRAMP5), which encodes a natural resistance-associated macrophage protein. Functional analysis revealed that the defective transporter protein encoded by the mutant osnramp5 greatly decreases Cd uptake by roots, resulting in decreased Cd in the straw and grain. In addition, we developed DNA markers to facilitate marker-assisted selection of cultivars carrying osnramp5. When grown in Cd-contaminated paddy fields, the mutants have nearly undetectable Cd in their grains and exhibit no agriculturally or economically adverse traits. Because mutants produced by ion-beam radiation are not transgenic plants, they are likely to be accepted by consumers and thus represent a practical choice for rice production worldwide.

Original languageEnglish
Pages (from-to)19166-19171
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number47
DOIs
Publication statusPublished - 2012 Nov 20

ASJC Scopus subject areas

  • General

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