The pZPsC/pZCycH double transformants exhibited a more
variable carotenoid pattern. This ranged from phenotypes that
are similar to the ones from the single transformations to
others that contain -carotene as almost the only carotenoid.
Our line z11b is an example of the latter also representing up
to now the winner in quantitative terms. A carotenoid content
of 1.6 g/g dry rice endosperm was determined. From a
nutritional point of view, it is not yet clear whether lines
producing provitamin A (-carotene) or lines possessing additionally
zeaxanthin and lutein are to be selected, because it
has been discovered during recent years that these xanthophylls
are present in the eye’s macula and, hence, their defi-
ciency may contribute to macular degeneration, leading to
blindness (8). In this respect, lutein and zeaxanthin, therefore,
may represent valuable compounds for human health