Overexpression of rice phytochrome A in Arabidopsis: Diverse role in multiple physiological responses

Phytochrome a predominantly mediates responses to prolonged far-red light such as the inhibition of hypocotyl elongation. it also acts in controlling responses to fr light pulses. to investigate to what extent rice phytochrome a complements the function of arabidopsis phytochrome a,we examined hypocotyl elongation growth,seed germination,and greening in etiolated seedlings of phya-211 mutant plants,wt and two kinds of transgenic plants in which wt and phya-211 mutants overexpressed rice phya cdna. we found that ectopic expression of rice phytochrome a could partially rescue the sensitivity of phya-211 mutant hypocotyls to prolonged far-red light and replace arabidopsis phytochrome a in the promotion of seed germination and recovery of the ability to de-etiolate. moreover,under end-of-day far-red light (eod-fr),the exogenous rice phytochrome a was found to restore some aspects of growth in phya-211 mutants,such as hypocotyl elongation,petiole elongation and flowering time. the diverse role of rice phytochrome a in the physiological responses of arabidopsis implies the substitution of phytochrome signaling between monocots and dicots.