Abstract
Phytochromes are one of the major photoreceptor families in plants. Phytochromes translocate from the cytoplasm into the nucleus in a light-dependent manner and transmit a signal. However, the details of phytochrome signaling in the late-vegetative phase remain unknown. VOZ was isolated as a phytochrome-interacting factor by screening focused on flowering. Arabidopsis possesses two VOZ genes, VOZ1 and VOZ2. VOZ functions downstream of phyB and upregulates the flowering promoting factor FT. We analyzed the subcellular localization of functional VOZ, using a nuclear localization signal (NLS) and a nuclear export signal (NES). Only VOZ-NLS complemented the late flowering phenotype of voz1 voz2 mutants. However, the accumulation of VOZ protein was detected for the NES fusion, but not for the NLS fusion. Moreover, the VOZ-NLS protein accumulation increased detectable levels with the treatment of proteasome inhibitor. These results indicate that VOZ functions in the nucleus but VOZ protein is subjected to degradation once translocated into the nucleus. We are performing the expression analysis of FT upstream factors. We would like to discuss about the VOZ function in flowering pathway.
