Kolesnikov Y. Role of phospholipase D in biological action of cytokinins

Phospholipase D cells of plants as a component of the alarm cascade cytokinin in cells of an amaranth. An establishment of participation phospholipase D in cytokinin signal transduction. Methods labeled isotopes (33Р): introduction of a label, thin-layer chromatography labeled phospholipids, autoradiography and scintillation calculation, the biotest on cytokinin. The effect of cytokinin on changes in phospholipase D activity - as measured by radioactivity of its product phosphatidylbutanol - was investigated in cotyledons of amaranthus (Amaranthus caudatus L.) seedlings. Rapid increase of phospholipase D activity was found during the early 5 minutes of cytokinin treatment that was maintained at 30 minutes comparing to untreated plants. The results indicate participation of phospholipase D in early stages of cytokinin signaling. Regulation of phospholipase D, activated by cytokinin, was studied, specifically the role of cofactors - calcium and phosphatidylinositol 4,5-bisphosphate. Pretreatment of plants with calcium channel blocker verapamil and extracellular calcium chelator EGTA reduced cytokinin-dependent phospholipase D activation. Application of neomycin, chelator of phosphatidylinositol 4,5-bisphosphate, also caused dramatic inhibition of its enzymatic activity. Sensitivity of phosphatidylbutanol accumulation to calcium and phosphatidylinositol 4,5-bisphosphate availability suggests a role of different phospholipase D isoenzymes, dependent on these cofactors, in cytokinin signaling. Sphere of use: bioorganic chemistry, physiology of plants.