One implication of the transformations described above is
that the cotransformation is not necessary in rice endosperm,
but that a construct containing psy and crtI might be sufficient
to install the entire pathway. Accordingly, we reconstructed
the plasmid pB19hpc with the following modifications. First,
the hygromycin-selectable marker gene was exchanged against
the PMI gene; concomitantly, the selection procedure for PMI
was established for rice (12). Second, the nptII gene, left
unnecessarily within the border sequences of the old construct
(Fig. 2), was removed. New single lines have been produced
recently showing again yellow color (Fig. 4). Carotenoid
quantification showed again in the best performing segregating
F0 line, a carotenoid content of 1.6 g carotenoid/g dry rice
endosperm.