In this paper, we compare positive, red-light-induced
phototropsim and negative, blue-light-induced phototropism
in Arabidopsis roots. Our results show that the red-lightabsorbing
phytochrome (phy) family of photoreceptors
(Quail, 2002), specifically phyA and phyB, play a role in
both types of phototropic responses in Arabidopsis roots.