Abstract
We are interested in how different are the light signaling pathways in non-photosynthetic plants from those in photosynthetic plants. We have been investigating phytochrome A from a holoparasitic plant, Orobanche minor. In this study, we observed its physiological responses to red/far-red light. Germination of O. minor was inhibited by continuous and pulse red light whereas far-red light reversibly counteracts the effect of red light. From the result, it is indicated that phytochrome-mediated signaling systems work in the non-photosynthetic plant. The hypocotyl elongation was inhibited by white and far-red light but not by red light. Anthocyanin level was increased by white and far-red light and not by red light. So, it seems that high irradiation response to red light is lacked in O. minor during the stem elongation process. These results suggest that O. minor respond to red/far-red light in different way from that in photosynthetic plant such as Arabidopsis.