Proteomics of Arabidopsis redox proteins in response to methyl jasmonate Sophie Alvarez a,1 , Mengmeng Zhu a , Sixue Chen a,b, ⁎ a Department of Botany and Zoology, Genetics Institute, The Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32611, USA b College of Life Sciences, Heilongjiang University, Harbin, China ARTICLE INFO ABSTRACT Article history: Received 23 April 2009 Accepted 15 July 2009 Protein redox regulation is increasingly recognized as an important switch of protein activity in yeast, bacteria, mammals and plants. In this study, we identified proteins with potential thiol switches involved in jasmonate signaling, which is essential for plant defense. Methyl jasmonate (MeJA) treatment led to enhanced production of hydrogen peroxide in Arabidopsis leaves and roots, indicating in vivo oxidative stress. With monobromobimane (mBBr) labeling to capture oxidized sulfhydryl groups and 2D gel separation, a total of 35 protein spots that displayed significant redox and/or total protein expression changes were isolated. Using LC–MS/MS, the proteins in 33 spots were identified in both control and MeJA-treated samples. By comparative analysis of mBBr and SyproRuby gel images, we were able to determine many proteins that were redox responsive and proteins that displayed abundance changes in response to MeJA. Interestingly, stress and defense proteins constitute a large group that responded to MeJA. In addition, many cysteine residues involved in the disulfide dynamics were mapped based on tandem MS data. Identification of redox proteins and their cysteine residues involved in the redox regulation allows for a deeper understanding of the jasmonate signaling networks. © 2009 Elsevier B.V. All rights reserved. Keywords: Arabidopsis 2-DE Mass Spectrometry Methyl jasmonate Redox proteins 1. Introduction Plants produce jasmonic acid and methyl jasmonate (MeJA) in response to many abiotic and biotic stresses, particularly pathogen and insect herbivores [1,2]. Jasmonates are plant hormones biosynthesized from linolenic acid through the octadecanoid pathway [3]. They function as signaling mole- cules to activate genes involved in plant defense responses [4,5]. Over the past decades, intensive research has been focused on the jasmonate signaling pathway in Arabidopsis and tomato [6–8]. The perception of stress signal, the induction and regulation of jasmonate biosynthesis, and the genes differentially expressed by jasmonates have been well-studied [3,6,7,9–11]. However, the molecular details of downstream regulatory proteins and pathways remain to be discovered. It was suggested in 1994 that jasmonates could induce oxidative stress in parsley suspension cells [12]. Later, jasmonate induced hydrogen peroxide (H 2 O 2 ) accumulation was observed in the cell wall of tomato plants [13].H 2 O 2 , the most stable form of reactive oxygen species (ROS), is well known to function as a signaling molecule to activate cellular antioxidant mechanisms, and can be used as an indicator of cellular oxidative stress [14]. JOURNAL OF PROTEOMICS 73 (2009) 30 – 40 1874-3919/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jprot.2009.07.005 ⁎ Corresponding author. Genetics Institute, University of Florida, 1376 Mowry Road, Room 438, Gainesville, FL 32610, USA. Tel.: +1 352 273 8330; fax: +1 352 273 8284. E-mail address: schen@ufl.edu (S. Chen). 1 Current address: Donald Danforth Plant Science Center, St Louis, MO 63132, USA. available at www.sciencedirect.com www.elsevier.com/locate/jprot