The Role Of Ion Channel And ROS In EATP-regulated Stomotal Movement Of Vicia Faba

Guard cell is a good model system for research of plant cell signal transduction. A variety of signaling molecules can regulate stomatal movement, Ca₂₊channels and reactive oxygen species (ROS) play important roles in signaling pathways of these stimuli. Extracellular ATP (eATP) played an important role in plant development and stress resistance. In order to investigate the effect of eATP on stomatal movement, and its possible signal transduction mechanisms. Vicia faba was used as material, the effect of added ATP on stomatal movement was investigated. The effect of eATP on ROS generation and plasma membrane calcium channels activities in guard cells was investigated by using confocal laser scanning microscopy and voltage patch-clamping. And the relationship between ROS and calcium channels was discussed.As the result of experiment,300-1000μmol/L ATP promoted stomatal opening remarkably. Apyrase or Hexokinase inhibited stomatal opening markedly. Indicating that exogenous ATP promote stomatal opening, and endogenous eATP is necessary for normal stomatal movement.The eATP promoted stomatal opening was remarkably inhibited by dipheyleneiodonium (DPI) or dithiothreitol (DTT) pretreatment, indicating that ROS may play a key role in this process. ROS concentration in guard cells increased after ATP treatment, confirming that ROS which generated by NADPH oxidase may be an important component in eATP signal transduction pathway.By using whole-cell voltage-clamping, hyperpolarization-activated Ca₂₊channels in plasma membrane of Vicia faba guard cell was detected. Added ATP activated Ca2+ conductance remarkably. The eATP-induced activation of calcium channel was remarkably inhibited by DTT or DPI. Indicating that ROS plays a crucial role in eATP induced activation of Ca₂₊channels. Based on these results, we suggest that, as an extracellular messenger, eATP may promote stomatal opening through ROS and calcium signaling.