title: Stomatal closure induced by phytosphingosine-1-phosphate and sphingosine-1-phosphate depends on nitric oxide and pH of guard cells in Pisum sativum.
abstract: Phyto-S1P and S1P induced stomatal closure in epidermis of pea ( Pisum sativum ) by raising the levels of NO and pH in guard cells. Phosphosphingolipids, such as phytosphingosine-1-phosphate (phyto-S1P) and sphingosine-1-phosphate (S1P), are important signaling components during drought stress. The biosynthesis of phyto-S1P or S1P is mediated by sphingosine kinases (SPHKs). Although phyto-S1P and S1P are known to be signaling components in higher plants, their ability to induce stomatal closure has been ambiguous. We evaluated in detail the effects of phyto-S1P, S1P and SPHK inhibitors on signaling events leading to stomatal closure in the epidermis of Pisum sativum. Phyto-S1P or S1P induced stomatal closure, along with a marked rise in nitric oxide (NO) and cytoplasmic pH of guard cells, as in case of ABA. Two SPHK inhibitors, DL-threo dihydrosphingosine and N',N'-dimethylsphingosine, restricted ABA-induced stomatal closure and prevented the increase of NO or pH by ABA. Modulators of NO or pH impaired both stomatal closure and increase in NO or pH by phyto-S1P/S1P. The stomatal closure by phyto-S1P/S1P was mediated by phospholipase D and phosphatidic acid (PA). When present, PA elevated the levels of pH, but not NO of guard cells. Our results demonstrate that stomatal closure induced by phyto-S1P and S1P depends on rise in pH as well as NO of guard cells. A scheme of signaling events initiated by phyto-S1P/S1P, and converging to cause stomatal closure, is proposed.
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
authors.forename: Mallikarjuna Rao
authors.initials: MR
authors.lastname: Puli
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
authors.forename: Pidakala
authors.initials: P
authors.lastname: Rajsheel
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
authors.forename: Vetcha
authors.initials: V
authors.lastname: Aswani
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
authors.forename: Srinivas
authors.initials: S
authors.lastname: Agurla
authors.affiliation: Department of Applied Biological Sciences, Tokyo University of Science, Chiba Ken, Noda, 278-8510, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kuchitsu
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India. asrsl@uohyd.ernet.in.
authors.forename: Agepati S
authors.initials: AS
authors.lastname: Raghavendra
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000704:Analysis of Variance; D005456:Fluorescent Dyes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008246:Lysophospholipids / Q000378:metabolism / Q000494:pharmacology*; D018613:Microscopy, Confocal; D009569:Nitric Oxide / Q000378:metabolism*; D018532:Pisum sativum / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology; D054046:Plant Stomata / Q000187:drug effects* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D013997:Time Factors; D000099157:Sphingosine Kinase
chemical_list: D000040:Abscisic Acid; D005456:Fluorescent Dyes; D008246:Lysophospholipids; D009569:Nitric Oxide; D017853:Phosphotransferases (Alcohol Group Acceptor); D010937:Plant Growth Regulators; D013110:Sphingosine; D000099157:Sphingosine Kinase; C117422:phytosphingosine-1-phosphate; C060506:sphingosine 1-phosphate
keywords: Abscisic acid; LCB signaling; Pea; Phosphosphingolipids; Sphingosine kinase; Stomata