MEDVEDEV, S.S., TANKELYUN, O.V., BATOV, A.Y., VORONINA, O.V., MARTINEC, Jan, MACHÁČKOVÁ, Ivana. Ionophorous functions of phosphatidic acid in the plant cell. Russian Journal of Plant Physiology. 2006, 53(1), 39-47. ISSN 1021-4437. E-ISSN 1608-3407.

Effects of phosphatidic acid (PA), a product of phospholipase D activity, on Ca2+ and H+ transport were investigated in membrane vesicles obtained from roots and coleoptiles of maize (Zea mays L.). Calcium flows were measured with fluorescent probes indo-1 and chlorotetracycline loaded into the vesicles and added to the incubation medium, respectively. Phosphatidic acid (50-500 mu M) was found to induce downhill flow of Ca2+ along the concentration gradient into the plasma membrane vesicles and endomembrane vesicles (tonoplast and endoplasmic reticulum). Protonophorous functions of PA were probed with acridine orange. First, the ionic H+ gradient was created on the tonoplast vesicles by means of H+-ATPase activation with Mg-ATP addition. Then. the vesicles were treated with 25-100 mu M PA, which induced the release of protons from tonoplast c vesicles and dissipation of the proton gradient. Thus, PA could function as an ionophore and was able to transfer Ca2+ and H+ across plant cell membranes along concentration gradients of these ions. The role of PA in mechanisms of intracellular signaling in plants is discussed.