Abstract
Side branch formation in the moss Physcomitrella patens was shown to be light-dependent. Two cryptochrome genes, CRY1a and CRY1b, were identified in this organism. Using gene-knock-out technique, these cryptochromes were shown to be responsible for the blue light-induced side branch formation (Imaizumi et al., 2002).
In the present study, we found two different types of red light effects on blue light-induced branch formation. The number of branches increased when red light was applied together with the inductive blue light. By partial irradiation of a cell, the photoreceptive site for the red light promotion effect was found to locate around the nucleus. Next, when polarized red light was given with blue light, branching position was determined by the vibration plane of polarized red light. These results indicate that red light receptor(s) are also involved in the light-induced side branch formation.
