Significant progress has been made in our understanding
of carotenoid biosynthesis in plants. Nevertheless, we
still lack fundamental knowledge on various aspects of
this process. More information is needed to answer a
number of questions. Where exactly within the plastids
do the different enzymes operate? Do the enzymes of
the pathway function in protein complexes? Which
metabolic regulations take place at the enzyme level?
What are the interactions between the carotenoid pathway
and other metabolic pathways? What are the
molecular components that control the expression of
carotenoid genes? Answering these and other questions
will shed light on an important metabolic pathway and
improve our capability to manipulate carotenoids in crop
plants.