Abstract
Rice has three phytochromes, PHYA, PHYB and PHYC. Expression analysis of PHYA protein has been difficult because the amount of PHYA is low in light-grown plants. We improved method of protein extraction and were able to detect PHYA protein by immunoblot in green leaf in rice. We examined the expression of PHYA in plants with fully expanded fifth leaf. Amount of PHYA in leaf sheath (LS) was higher than that in leaf blade (LB). The fourth and fifth LB contained the same level of PHYA, but a higher level was detected in the sixth LB, which were enclosed by the fifth LS. In the fifth LB and LS, PHYA decreased during the light-phase and increased during the dark-phase, and the change of PHYA transcript showed correlation with the change of PHYA protein in LB. But in LS, the change of PHYA transcript showed only a weak correlation with the change of PHYA protein. It has been reported that PHYA is suppressed by PHYB in pea. We examined this phenomenon using phyB, phyC and phyBphyC mutants, and found that the expression of PHYA was suppressed mainly by PHYB and partly by PHYC. These results indicate that further studies are needed to elucidate the function of PHYA in green leaf.
