Improving the nutritional value of Golden Rice through increased pro-vitamin A content


'Golden Rice' is a variety of rice engineered to produce β-carotene (pro-vitamin A) to help combat vitamin A deficiency1, and it has been predicted that its contribution to alleviating vitamin A deficiency would be substantially improved through even higher β-carotene content2. We hypothesized that the daffodil gene encoding phytoene synthase (psy), one of the two genes used to develop Golden Rice, was the limiting step in β-carotene accumulation. Through systematic testing of other plant psys, we identified a psy from maize that substantially increased carotenoid accumulation in a model plant system. We went on to develop 'Golden Rice 2' introducing this psy in combination with the Erwinia uredovora carotene desaturase (crtI) used to generate the original Golden Rice1. We observed an increase in total carotenoids of up to 23-fold (maximum 37 μg/g) compared to the original Golden Rice and a preferential accumulation of β-carotene.

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Figure 1: Expression of a psy transgene increases the carotenoid content of maize callus.
Figure 2: Carotenoid enhancement of the rice endosperm by transformation with psy orthologues and crtI.

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The authors would like to thank Will Parish, Erik Dunder, Dong Fang Chen and Annalisa Tiozzo for tissue culture, Karen Bacon and Fasica Woldeyes for plant growth, Melanie Watkins for plant assessment, Elek Bolygo for analytical advice, Ebun Eno-Amooquaye for western blot analysis, Keith Ward for advice on statistics and others who gave technical support to the research. We would also like to thank Peter Beyer, Lu Liu and John Ray for plasmids. We thank Peter Beyer for discussion on the manuscript.

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Correspondence to Rachel Drake.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Carotenoid biosynthesis in plants (PDF 64 kb)

Supplementary Fig. 2

Expression of CRTI and maize PSY proteins in rice endosperm (PDF 192 kb)

Supplementary Table 1

Carotenoid composition of maize callus expressing a Psy transgene (PDF 61 kb)

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Paine, J., Shipton, C., Chaggar, S. et al. Improving the nutritional value of Golden Rice through increased pro-vitamin A content. Nat Biotechnol 23, 482–487 (2005).

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