Abstract
Phytochromes are one of the photoreceptors sensing red- and far-red-light and encoded by small gene families in higher plants. In the case of rice, three genes (PHYA, PHYB, PHYC) encode phytochrome apoproteins. Each member of rice phytochromes has distinct as well as cooperative roles in light perception. In this study, we made each promoter-GUS transgenic rice plants to analyze the expression patterns of each phytochromes. PHYA showed vascular bundle specific expression patterns at almost all tissues and developmental stages while PHYB and PHYC showed lower expression and tissue specificity than PHYA. The results of extensive analysis indicate that the vascular bundle specific patterns of PHYA are affected by light circumstance. In order to discuss biological meanings of the expression patterns, we tested complementation of each phytochrome mutations with own or swapped promoter-phytochrome cDNA transgene. Photomorphogenesis of T1 seedlings indicated that PHYA promoter could regulate enough for PHYB function but PHYB promoter could not for PHYA. However, the results of flowering time complementation showed a partial effect of PHYB promoter on PHYA function.
