Please cite this article in press as: Kruk, J. et al., Function of isoprenoid quinones and chromanols during oxidative stress in plants, New Biotechnol. (2016), http://dx.doi.org/10.1016/ j.nbt.2016.02.010 New Biotechnology  Volume 00, Number 00  March 2016 RESEARCH PAPER Function of isoprenoid quinones and chromanols during oxidative stress in plants Jerzy Kruk Q1 1 , Renata Szyman ´ ska 2 , Beatrycze Nowicka 1 and Jolanta Dluz ˙ewska 1 1 Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krako ´ w, Poland 2 Department of Medical Physics and Biophysics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Reymonta 19, 30-059 Krako ´ w, Poland Isoprenoid quinones and chromanols in plants fulfill both signaling and antioxidant functions under oxidative stress. The redox state of the plastoquinol pool (PQ-pool), which is modulated by interaction with reactive oxygen species (ROS) during oxidative stress, has a major regulatory function in both short- and long-term acclimatory responses. By contrast, the scavenging of ROS by prenyllipids affects signaling pathways where ROS play a role as signaling molecules. As the primary antioxidants, isoprenoid quinones and chromanols are synthesized under high-light stress in response to any increased production of ROS. During photo-oxidative stress, these prenyllipids are continuously synthesized and oxidized to other compounds. In turn, their oxidation products (hydroxy-plastochromanol, plastoquinol-C, plastoquinone-B) can still have an antioxidant function. The oxidation products of isoprenoid quinones and chromanols formed specifically in the face of singlet oxygen, and can be indicators of singlet oxygen stress. Introduction Q2 In a natural environment plants have to cope with conditions that are far from optimal for their growth, which are called stress conditions. The most frequent abiotic stresses are caused by excess light, temperature (low and high) and drought [1]. All these unfavorable conditions result in the enhanced production of reactive oxygen species (ROS) that may have deleterious effects [2]. To prevent this, under stress conditions plants produce elevat- ed levels of a variety of antioxidant molecules. These are enzymatic and low-molecular compounds, which may be water-soluble (e.g. ascorbate (Asc), glutathione (GSH)) or lipid-soluble (carotenoids, isoprenoid quinones, isoprenoid chromanols) [3]. As the primary sites of ROS formation in cells are lipid membranes, membrane- localized antioxidants form the first line of defense against ROS [4]. Among isoprenoid quinones and chromanols with antioxidant properties, tocopherols were the first to be recognized [5,6]. How- ever, other compounds with a similar function, such as plastoqui- nol (PQH 2 ), plastochromanol-8 (PC-8) or its derivative hydroxy- plastochromanol (PC-OH), have recently been identified (Fig. 1). They are especially abundant in plants exposed to high-light stress [4,7,8]. Besides their antioxidant function, isoprenoid quinones and chromanols may also have signaling functions during the response to oxidative stress [4,6,9]. Function of isoprenoid quinones and chromanols in signal transduction Plastoquinone and plastoquinol Plastoquinone (PQ) plays a central role in photosynthetic electron transport in chloroplasts and its redox state serves as the major signal-transducing component in both short- and long-term responses during photoacclimation processes, such as state Research Paper Corresponding author: Kruk, J. (jerzy.kruk@uj.edu.pl) http://dx.doi.org/10.1016/j.nbt.2016.02.010 www.elsevier.com/locate/nbt 1871-6784/ß 2016 Published by Elsevier B.V. 1