title: NADPH oxidase activity in pollen tubes is affected by calcium ions, signaling phospholipids and Rac/Rop GTPases.
abstract: Reactive oxygen species (ROS) generated by NADPH oxidase (NOX) are crucial for tip growth of pollen tubes. However, the regulation of NOX activity in pollen tubes remains unknown. Using purified plasma membrane fractions from tobacco and olive pollen and tobacco BY-2 cells, we demonstrate that pollen NOX is activated by calcium ions and low abundant signaling phospholipids, such as phosphatidic acid and phosphatidylinositol 4,5-bisphosphate in vitro and in vivo. Our data also suggest possible synergism between Ca(2+) and phospholipid-mediated NOX activation in pollen. Rac/Rop small GTPases are also necessary for normal pollen tube growth and have been proposed to regulate ROS production in root hairs. We show here elevated ROS formation in pollen tubes overexpressing wild-type NtRac5 and constitutively active NtRac5, while overexpression of dominant-negative NtRac5 led to a decrease of ROS in pollen tubes. We also show that PA formed by distinct phospholipases D (PLD) is involved in pathways both upstream and downstream of NOX-mediated ROS generation and identify NtPLDδ as a PLD isoform acting in the ROS response pathway.
authors: Institute of Experimental Botany, vvi, Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic. potocky@ueb.cas.cz
authors: Martin
authors: M
authors: Potocký
authors: Přemysl
authors: P
authors: Pejchar
authors: Małgorzata
authors: M
authors: Gutkowska
authors: María José
authors: MJ
authors: Jiménez-Quesada
authors: Andrea
authors: A
authors: Potocká
authors: Juan de Dios
authors: Jde D
authors: Alché
authors: Benedikt
authors: B
authors: Kost
authors: Viktor
authors: V
authors: Žárský
mesh_terms: D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology* / Q000378:metabolism; D015870:Gene Expression; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism*; D031658:Olea / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D010743:Phospholipids / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D053205:Pollen Tube / Q000201:enzymology* / Q000254:growth & development; D020033:Protein Isoforms; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D014026:Nicotiana / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D010743:Phospholipids; D010940:Plant Proteins; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D020559:Monomeric GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D002118:Calcium