Abstract
Phytochrome is a major informational photoreceptor in plants. The phytochrome molecule has two domains: the N-terminal photosensory domain and the C-terminal domain which contains signaling motifs such as a kinase domain. The latter has been widely believed to transduce the signal to downstream components. Our recent study clearly demonstrated that the N-terminal domain, but not the C-terminal domain, of Arabidopsis phytochrome B (phyB) transduces the signal, which forces us to reconsider our view on phytochrome. However, nothing has been known about the molecular mechanism of this phenomenon. Hence, mainly by using a genetic screening strategy, we are addressing the following two points: 1) which amino acid residue within the N-terminal domain of phyB is directly involved in signal transfer? and 2) what is the downstream signaling component responsible for it? We believe these analyses will give us a clue to unravel the long-standing mystery of phytochrome signal transduction.
