Several studies have shown that phytochromes play a
role in the modulation of the phototropic response in
hypocotyls, and the results in this paper extend these
results to root phototropism as well. As an example,
Janoudi et al.(1997) demonstrated that phyA and phyB
are required for the normalexpression of hypocotyl
phototropism and suggest a complex interaction between
blue-light and red-light mediated processes in phototropism.
Furthermore, Parks et al.(1996) have shown that phyA
regulates red-light induction of phototropic enhancement
in hypocotyls.