title: ABA, hydrogen peroxide and nitric oxide signalling in stomatal guard cells.
abstract: Increased synthesis and redistribution of the phytohormone abscisic acid (ABA) in response to water deficit stress initiates an intricate network of signalling pathways in guard cells leading to stomatal closure. Despite the large number of ABA signalling intermediates that are known in guard cells, new discoveries are still being made. Recently, the reactive oxygen species hydrogen peroxide (H2O2) and the reactive nitrogen species nitric oxide (NO) have been identified as key molecules regulating ABA-induced stomatal closure in various species. As with many other physiological responses in which H2O2 and NO are involved, stomatal closure in response to ABA also appears to require the tandem synthesis and action of both these signalling molecules. Recent pharmacological and genetic data have identified NADPH oxidase as a source of H2O2, whilst nitrate reductase has been identified as a source of NO in Arabidopsis guard cells. Some signalling components positioned downstream of H2O2 and NO are calcium, protein kinases and cyclic GMP. However, the exact interaction between the various signalling components in response to H2O2 and NO in guard cells remains to be established.
authors.affiliation: Centre for Research in Plant Science, Faculty of Applied Sciences, University of the West of England, Bristol, Coldharbour Lane, Bristol BS16 1QY, UK. radhika.desikkan@uwe.ac.uk
authors.forename: Radhika
authors.initials: R
authors.lastname: Desikan
authors.forename: Man-Kim
authors.initials: MK
authors.lastname: Cheung
authors.forename: Jo
authors.initials: J
authors.lastname: Bright
authors.forename: Dan
authors.initials: D
authors.lastname: Henson
authors.forename: John T
authors.initials: JT
authors.lastname: Hancock
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Neill
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D018525:Germination / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D009569:Nitric Oxide / Q000494:pharmacology*; D059828:Plant Cells; D063245:Plant Development; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018521:Plant Physiological Phenomena; D010944:Plants / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
chemical_list: D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D000040:Abscisic Acid