Single genetic locus improvement of iron, zinc and \u03b2-carotene content in rice grains

Simrat Pal Singh,Wilhelm Gruissem,Navreet K Bhullar

doi:10.1038/s41598-017-07198-5

Abstract

Nearly half of the world’s population obtains its daily calories from rice grains, which lack or have insufficient levels of essential micronutrients. The deficiency of micronutrients vital for normal growth is a global health problem, and iron, zinc and vitamin A deficiencies are the most prevalent ones. We developed rice lines expressing Arabidopsis NICOTIANAMINE SYNTHASE 1 (AtNAS1), bean FERRITIN (PvFERRITIN), bacterial CAROTENE DESATURASE (CRTI) and maize PHYTOENE SYNTHASE (ZmPSY) in a single genetic locus in order to increase iron, zinc and β-carotene content in the rice endosperm. NAS catalyzes the synthesis of nicotianamine (NA), which is a precursor of deoxymugeneic acid (DMA) iron and zinc chelators, and also chelate iron and zinc for long distance transport. FERRITIN provides efficient storage of up to 4500 iron ions. PSY catalyzes the conversion of GGDP to phytoene, and CRTI performs the function of desaturases required for the synthesis of β-carotene from phytoene. All transgenic rice lines have significantly increased β-carotene, iron, and zinc content in the polished rice grains. Our results establish a proof-of-concept for multi-nutrient enrichment of rice grains from a single genetic locus, thus offering a sustainable and effective approach to address different micronutrient deficiencies at once.

Highlights

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We developed rice lines expressing Arabidopsis NICOTIANAMINE SYNTHASE 1 (AtNAS1), bean FERRITIN (PvFERRITIN), bacterial CAROTENE DESATURASE (CRTI) and maize PHYTOENE SYNTHASE (ZmPSY) in a single genetic locus in order to increase iron, zinc and β-carotene content in the rice endosperm
NAS catalyzes the synthesis of nicotianamine (NA), which is a precursor of deoxymugeneic acid (DMA) iron and zinc chelators, and chelate iron and zinc for long distance transport

Summary

Journal Article

Single genetic locus improvement of iron, zinc and β-carotene content in rice grains. All transgenic rice lines have significantly increased β-carotene, iron, and zinc content in the polished rice grains. Iron, zinc and β-carotene levels are significantly increased in the rice endosperm This establishes a proof of concept for adapting the biofortification approaches to simultaneously address several important micronutrient deficiencies. In order to assess if increased iron and β-carotene synthesis can be combined in rice endosperm, the high-iron NFP rice[18] expressing AtNAS1 and PvFERRITIN was super-transformed with a construct containing PaCRTI and ZmPSY (CP lines). In comparison to the non-transgenic sibling and Nipponbare controls, all transformed lines showed significantly higher iron content in the polished grains and with exception of three lines, the zinc content was increased. Phenotypic characterization of T2-generation transgenic plants grown in soil showed some variability for measured parameters such as days to flowering, plant height, tiller, 1000 grain weight (Supplementary Table S2)

Discussion

Materials and Methods

Author Contributions

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Additional Information