Carotenoid enhancement of the rice endosperm (a) The T-DNA comprised rice glutelin promoter (Glu) intron of catalase gene castor bean (I) E. uredovora crtI functionally fused to the pea RUBISCO chloroplast transit peptide (SSUcrtI) phytoene synthase from each of five plant species (psy), nos terminator, selectable marker cassette maize polyubiquitin (Ubi1) promoter with intron, hygromycin resistance (hpt) and nos terminator.

Figure 2. Carotenoid enhancement of the rice endosperm by transformation with psy orthologues and crtI.
(a) Schematic diagram of the T-DNAs used to generate transgenic rice plants. The T-DNA comprised the rice glutelin promoter (Glu) and the first intron of the catalase gene from castor bean (I), E. uredovora crtI functionally fused to the pea RUBISCO chloroplast transit peptide (SSUcrtI) and a phytoene synthase from each of five plant species (psy), with a nos terminator, as well as a selectable marker cassette comprising the maize polyubiquitin (Ubi1) promoter with intron, hygromycin resistance (hpt) and nos terminator. (b) Photograph of polished wild-type and transgenic rice grains containing the T-DNA (as above) with the daffodil psy (Np) or maize psy (Zm) showing altered color due to carotenoid accumulation. (c) Histogram showing the total carotenoid content of T1 rice seed containing a T-DNA (as above) with the psy gene from either rice, maize, pepper, tomato or daffodil from the five events with the highest carotenoid content for each T-DNA. Measurement error tended to be proportional to absolute carotenoid content and pooling across all 25 transformants resulted in a measurement standard error of   6.3% approximately. dwt, dry weight. (d) Schematic diagram of the T-DNA in pSYN12424 used to create Golden Rice 2. The T-DNA components were as described above with a selectable marker cassette comprising the maize polyubiquitin (Ubi1) promoter with intron, phosphomannose isomerase gene (pmi) and nos terminator. The use of an intron was abandoned because it was shown to have no effect on carotenoid accumulation (data not shown).