Please cite this article in press as: J. Matouˇ sková, et al., Changes in actin dynamics are involved in salicylic acid signaling pathway, Plant Sci. (2014), http://dx.doi.org/10.1016/j.plantsci.2014.03.002 ARTICLE IN PRESS G Model PSL 8942 1–9 Plant Science xxx (2014) xxx–xxx Contents lists available at ScienceDirect Plant Science j ourna l ho me pa ge: www.elsevier.com/locate/plantsci Changes in actin dynamics are involved in salicylic acid signaling pathway Jindˇ riˇ ska Matouˇ sková a,d , Martin Janda a , Radovan Fiˇ ser b , Vladimír ˇ Saˇ sek c , Q1 Daniela Kocourková c , Lenka Burketová c , Jiˇ rina Duˇ sková d , Jan Martinec c , Olga Valentová a,∗ a Department of Biochemistry and Microbiology, Institute of Chemical Technology Prague, Technická 3, 166 28 Prague 6, Czech Republic b Charles University in Prague, Faculty of Science, Albertov 2038/6, 128 00 Prague 2, Czech Republic c Institute of Experimental Botany, Academy of Science of the Czech Republic, Rozvojová 263, 165 02 Prague 6 – Lysolaje, Czech Republic d Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic a r t i c l e i n f o Article history: Received 3 December 2013 Received in revised form 7 February 2014 Accepted 1 March 2014 Available online xxx Keywords: Actin dynamics Salicylic acid PR genes Phosphatidic acid a b s t r a c t Changes in actin cytoskeleton dynamics are one of the crucial players in many physiological as well as non-physiological processes in plant cells. Positioning of actin filament arrays is necessary for successful establishment of primary lines of defense toward pathogen attack, depolymerization leads very often to the enhanced susceptibility to the invading pathogen. On the other hand it was also shown that the disruption of actin cytoskeleton leads to the induction of defense response leading to the expression of PATHOGENESIS RELATED proteins (PR). In this study we show that pharmacological actin depolymeriza- tion leads to the specific induction of genes in salicylic acid pathway but not that involved in jasmonic acid signaling. Life imaging of leafs of Arabidopsis thaliana with GFP-tagged fimbrin (GFP-fABD2) treated with 1 mM salicylic acid revealed rapid disruption of actin filaments resembling the pattern viewed after treatment with 200 nM latrunculin B. The effect of salicylic acid on actin filament fragmentation was prevented by exogenous addition of phosphatidic acid, which binds to the capping protein and thus pro- motes actin polymerization. The quantitative evaluation of actin filament dynamics is also presented. © 2014 Published by Elsevier Ireland Ltd. 1. Introduction During coevolution with their natural enemies, plants evolved very complex and multilevel mechanisms to defense themselves, resulting in relatively very low success rate of invaders. Besides the constitutively based defense such as production of antimicrobial metabolites or structural barriers, plants are endowed with wide range of inducible mechanisms leading to the immune response to the invader. These processes are triggered by the recognition of pathogen common structures; pathogen or microbe associated molecular patterns (PAMPs or MAMPs). These structural deter- minants are perceived by pattern recognition receptors (PRRs) which in turn initiate downstream early events leading to immune response called PAMP-triggered immunity (PTI). Pathogens are able to overcome PTI by introducing effector molecules into the plant cell promoting the virulence of the pathogen. Plants in turn ∗ Corresponding author. Tel.: +420 220445102; fax: +420 220445167. Q2 E-mail address: olga.valentova@vscht.cz (O. Valentová). produce R proteins (resistance proteins) capable to eliminate the effect of effectors [1]. These early events triggered by pathogen attack are followed by the activation of signaling cascades which are regulated by plant hormones; key players in these processes are salicylic acid (SA), jasmonic acid (JA) and/or ethylene (ET) [2]. These hormones regulate signaling pathways which lead to the massive reprogramming of transcriptome and the expression of defense genes (PATHOGENESIS RELATED, PR) [3,4]. In Arabidopsis PR-1 (anti- fungal with unknown function), PR-2 (beta-1,3-glucanase) and PR-5 (thaumatin) are induced by salicylic acid, whereas PR-3 (chiti- nase), PR-4 (chitinase) and PR-12 (defensin, PDF1.2) are induced by jasmonic acid [5]. JA responsive gene PDF1.2 is associated with enhanced resistance to necrotrophic pathogens, the response to mechanical damage leads to the induction of vegetative storage protein (VSP2) [6–8]. SA also triggers induction of some WRKY transcription factors [9]. Transcription of two of them, WRKY38 and WRKY62 were shown to be induced by SA [10,11]. The actin cytoskeleton is a complex and dynamic filamentous structure of all eukaryotic cells. Besides its structural role, the actin cytoskeleton dynamics plays important roles not only in http://dx.doi.org/10.1016/j.plantsci.2014.03.002 0168-9452/© 2014 Published by Elsevier Ireland Ltd. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59