title: Enhanced Grain Iron Levels in Rice Expressing anIRON-REGULATED METAL TRANSPORTER, NICOTIANAMINE SYNTHASE, andFERRITINGene Cassette.
abstract: Micronutrient malnutrition is widespread, especially in poor populations across the globe, and iron deficiency anemia is one of the most prevalent forms of micronutrient deficiencies. Iron deficiency anemia has severe consequences for human health, working ability, and quality of life. Several interventions including iron supplementation and food fortification have been attempted and met with varied degrees of success. Rice, which is a staple food for over half of the world's population, is an important target crop for iron biofortification. The genetic variability of iron content in the rice germplasm is very narrow, and thus, conventional breeding has not been successful in developing high iron rice varieties. Therefore, genetic engineering approaches have targeted at increasing iron uptake, translocation, and storage in the rice endosperm. We previously reported thatAtIRT1, when expressed together withAtNAS1andPvFERRITIN(PvFER) in high-iron (NFP) rice, has a synergistic effect of further increasing the iron concentration of polished rice grains. We have now engineered rice expressingAtIRT1, AtNAS1, andPvFERas a single locus gene cassette and compared the resulting lines with transgenic lines expressingAtIRT1andPvFERgene cassettes. We also evaluated the efficacies of theMsENOD12Band nativeAtIRT1promoters for the expression ofAtIRT1in rice in both types of gene cassettes, and found the nativeAtIRT1promoter to be a better choice for driving theAtIRT1expression in our biofortification strategy. All the single insertion transgenic lines have significant increases of iron concentration, both in polished and unpolished grains, but the concerted expression ofAtIRT1, AtNAS1, andPvFERresulted to be a more effective strategy in achieving the highest iron increases of up to 10.46 μg/g dry weight. Furthermore, the transformed high iron lines grew better under iron deficiency growth conditions and also have significantly increased grain zinc concentration. Together, these rice lines have nutritionally relevant increases in polished grain iron and zinc concentration necessary to support human health.
authors.affiliation: Plant Biotechnology, Department of Biology, ETH Zurich Zurich, Switzerland.
authors.forename: Kulaporn
authors.initials: K
authors.lastname: Boonyaves
authors.affiliation: Plant Biotechnology, Department of Biology, ETH Zurich Zurich, Switzerland.
authors.forename: Ting-Ying
authors.initials: TY
authors.lastname: Wu
authors.affiliation: Plant Biotechnology, Department of Biology, ETH Zurich Zurich, Switzerland.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Gruissem
authors.affiliation: Plant Biotechnology, Department of Biology, ETH Zurich Zurich, Switzerland.
authors.forename: Navreet K
authors.initials: NK
authors.lastname: Bhullar
keywords: FERRITIN; IRON-REGULATED METAL TRANSPORTER; NICOTIANAMINE SYNTHASE; iron biofortification; rice