totropism and gravitropism is to use the microgravity conditions during spaceflight
(Correll et al. 2005; Kiss et al. 2007; see also Chapter 8 of this book). In these experi-
ments on the international space station, we plan to study the role of phytochromes in
phototropism and to determine whether red light affects phototropism directly or indi-
rectly by the attenuation of gravitropism. However, through the increased use of the new
tools of molecular and systems biology in the next decade, we should gain an even bet-
ter understanding of the basic mechanisms of phototropism, its relationship to gravitro-
pism, and its importance to plants.
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