title: Annexin 1 regulates the H2O2-induced calcium signature in Arabidopsis thaliana roots.
abstract: Hydrogen peroxide is the most stable of the reactive oxygen species (ROS) and is a regulator of development, immunity and adaptation to stress. It frequently acts by elevating cytosolic free Ca(2+) ([Ca(2+) ]cyt ) as a second messenger, with activation of plasma membrane Ca(2+) -permeable influx channels as a fundamental part of this process. At the genetic level, to date only the Ca(2) (+) -permeable Stelar K(+) Outward Rectifier (SKOR) channel has been identified as being responsive to hydrogen peroxide. We show here that the ROS-regulated Ca(2+) transport protein Annexin 1 in Arabidopsis thaliana (AtANN1) is involved in regulating the root epidermal [Ca(2+) ]cyt response to stress levels of extracellular hydrogen peroxide. Peroxide-stimulated [Ca(2+) ]cyt elevation (determined using aequorin luminometry) was aberrant in roots and root epidermal protoplasts of the Atann1 knockout mutant. Similarly, peroxide-stimulated net Ca(2+) influx and K(+) efflux were aberrant in Atann1 root mature epidermis, determined using extracellular vibrating ion-selective microelectrodes. Peroxide induction of GSTU1 (Glutathione-S-Transferase1 Tau 1), which is known to be [Ca(2+) ]cyt -dependent was impaired in mutant roots, consistent with a lesion in signalling. Expression of AtANN1 in roots was suppressed by peroxide, consistent with the need to restrict further Ca(2+) influx. Differential regulation of annexin expression was evident, with AtANN2 down-regulation but up-regulation of AtANN3 and AtANN4. Overall the results point to involvement of AtANN1 in shaping the root peroxide-induced [Ca(2+) ]cyt signature and downstream signalling.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
authors.forename: Siân L
authors.initials: SL
authors.lastname: Richards
authors.forename: Anuphon
authors.initials: A
authors.lastname: Laohavisit
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Mortimer
authors.forename: Lana
authors.initials: L
authors.lastname: Shabala
authors.forename: Stéphanie M
authors.initials: SM
authors.lastname: Swarbreck
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
authors.forename: Julia M
authors.initials: JM
authors.lastname: Davies
mesh_terms: D017302:Annexins / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016254:Mutagenesis, Insertional; D019441:Plant Epidermis / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011523:Protoplasts; D013312:Stress, Physiological; D015854:Up-Regulation
chemical_list: D017302:Annexins; D029681:Arabidopsis Proteins; D015220:Calcium Channels; D006861:Hydrogen Peroxide; C504971:annexin 1, Arabidopsis; D011188:Potassium; D002118:Calcium
keywords: Arabidopsis; annexin; calcium; glutathione; peroxide; root