Ca2+ transport in plant cells and mechanisms of transformation of phytochrome-induced photosignals

摘要

The recent data on the influence of phytochrome on the efficiency of Ca$+2$PLU$/ translocation across the membranes of oat protoplasts are given. Ca$+2$PLU$/ uptake in the protoplasts was shown to be influenced by the red light (R) illumination. This effect was reverted by the following far-red light (FR) illumination. To elucidate the sensitivity to phytochrome-controlling action the screening between the mechanisms of Ca$+2$PLU$/ transport across the plasma membranes of oat protoplasts, Na$+$PLU$//Ca$+2$PLU$/ and Ca$+2$PLU$//H$+$PLU$/ exchangers, Ca$+2$PLU$/-pump and Ca$+2$PLU$/-channel was done. It was established that phytochrome modulated the activity of Na$+$PLU$//Ca$+2$PLU$/-exchanger and Ca$+2$PLU$/-pump. The light-mediated oscillations of cytoplasmic Ca$+2$PLU$/ concentration in the oat protoplasts were demonstrated using fluorescence probe quin2 loaded into the cells and laser monitoring of fluorescence signal. The evidences were obtained that the oscillations were not the result of the elevation of cytoplasmic Ca$+2$PLU$/ concentration and had no connection with Ca$+2$PLU$/ pool of mitochondria. The possibility of the relation between the Ca$+2$PLU$/ oscillations and phosphoinositide metabolism in plant cell membranes is analyzed. The mechanisms of transformation of primary phytochrome signal into biological effects were discussed.