The sessile nature of plants has promoted the evolution of a wide range of mechanisms that enable plants to adapt to the changing environment.In particular, the light environment is highly dynamic and, therefore, plants have evolved several families of photoreceptors to detect almost all facets of light, such as quality, quantity, direction, and duration.Phytochromes are red (R) and far-red (FR) light photoreceptors in plants that play fundamental roles in modulating adaptive growth of plants in response to their changing light environment (Li et al., 2011).In the model plant Arabidopsis thaliana there are five phytochrome photoreceptors, named phytochrome A (phyA) to phyE.PhyA is photolabile, whereas phyB to phyE are photostable.PhyA and phyB, the two most abundant phytochromes, account for ～95％ of total phytochrome proteins in etiolated Arabidopsis seedlings and play the most important role in regulating seedling photomorphogenesis (Li et al., 2011).