Contents lists available at ScienceDirect Plant Physiology and Biochemistry journal homepage: www.elsevier.com/locate/plaphy Research article Highlight on the expression and the function of a novel MnSOD from diploid wheat (T. monococcum) in response to abiotic stress and heavy metal toxicity Sana Tounsi a , Kaouthar Feki b , Yosra Kamoun c , Mohamed Najib Saïdi a , Sonia Jemli d , Mouna Ghorbel a , Carine Alcon e , Faiçal Brini a,* a Biotechnology and Plant Improvement Laboratory, Centre of Biotechnology of Sfax (CBS)/University of Sfax, B.P ‘‘1177’’, 3018, Sfax, Tunisia b Laboratory of Legumes, Centre of Biotechnology Bordj Cedria, BP 901, 2050, Hammam Lif, Tunisia c Laboratory of Molecular Biotechnology of Eukaryotes, Centre of Biotechnology of Sfax, B.P ‘‘1177’’, 3018, Sfax, Tunisia d Laboratory of Microbial Biotechnology and Enzymes Engineering, Centre of Biotechnology of Sfax, B.P ‘‘1177’’, 3018, Sfax, Tunisia e Biochimie & Physiologie Moléculaire des plantes, PHIV platform, UMR 5004 CNRS/386 INRA/Supagro Montpellier / Université Montpellier 2, Campus Supagro-INRA, 34060, Montpellier Cedex 2, France ARTICLE INFO Keywords: Triticum monococcum MnSOD Abiotic stress Heavy metals Tolerance ABSTRACT Superoxide dismutases (SODs) play a pivotal role in improving abiotic stress tolerance in plant cells. A novel manganese superoxide dismutase gene, denoted as TmMnSOD, was identifed from Triticum monococcum. The encoded protein displayed high sequence identity with MnSOD family members and was highly homologous to TdMnSOD from durum wheat. Furthermore, the 3D structure analysis revealed that TmMnSOD displayed homotetramer subunit organization, incorporating four Mn 2+ ions. Notably, TmMnSOD structure contains predominantly alpha helices with three beta sheets. On the other hand, under stress conditions, TmMnSOD transcript level was signifcantly up-regulated by salt, oxidative and heavy metal stresses. At the functional level, TmMnSOD imparts tolerance of yeast and E. coli cells under diverse stresses. Promoter analysis of TmMnSOD gene showed the presence of a great number of salt and pathogen-responsive cis-regulatory elements, high- lighting the interest of this gene in breeding programs towards improved tolerance to salt stress in wheat. 1. Introduction Superoxide dismutases play crucial role in protecting plant cells from oxidative stress, which is generated during metabolic processes and under various environmental conditions. SODs are considered as the frst barrier of cellular defense against reactive oxygen species (ROS), catalyzing the dismutation of superoxide radical anions to hy- drogen peroxide (H 2 O 2 ) and oxygen (O 2 )(Del Rio et al., 2003; Gill and Tuteja, 2010; Mhamdi et al., 2010). Based on their metal cofactor in- teracting with their active sites, plant SODs are divided into three groups including iron SOD (FeSOD), copper–zinc SOD (Cu/ZnSOD) and manganese SOD (MnSOD) (Zhang et al., 2016a,b; Zhou et al., 2017). Each SOD group displays a diverse subcellular localization and struc- tural features in plants (Alscher et al., 2002; Zhang et al., 2016a,b). Cu/ ZnSODs and FeSODs are predominately found in chloroplast and cy- tosol, while MnSODs are mainly located in mitochondria (Gill and Tuteja, 2010; Miller, 2012). Comparison of amino acid sequences from these diferent SODs suggest that Mn and Fe SODs are considered as the ancient types of SODs, which probably evolved from the same ancestral enzyme, whereas Cu/ZnSODs sequences are diferent from Mn and FeSODs and probably have evolved separately in eukaryotes (Dehury et al., 2012a,b). In recent years, several SODs genes were identifed from various plant species such as Arabidopsis (Kliebenstein et al., 2010; Yadav et al., 2018), Medicago truncatula (Song et al., 2018), Sorghum bicolor (Filiz and Tombuloglu, 2015), cotton (Zhang et al., 2016a,b), rice (Nath et al., 2014; Yadav et al., 2018) and wheat (Feki et al., 2016; Wang et al., 2016; Tyagi et al., 2017). Genome wide analysis revealed that the numbers of SOD genes in Arabidopsis, rice, Sorghum and bread wheat are 8 (4 Cu/ZnSODs,2 FeSODs and 2 MnSODs), 8 (5 Cu/ZnSODs,2 FeSODs and 1 MnSOD), 8 (5 Cu/ZnSODs,2 FeSODs and 1 MnSOD) and 23 (14 Cu/ZnSODs,6 FeSODs and 3 MnSODs), respectively. The number of these genes varied among plant species and Cu/ZnSODs were con- sidered as the most predominant members compared to FeSODs and MnSODs (Gill and Tuteja, 2010; Gill et al., 2015; Verma et al., 2019). Transcript profling of SOD family from several plant species re- vealed that they play crucial role in scavenging ROS generated during plant growth and in response to various abiotic stresses. Their https://doi.org/10.1016/j.plaphy.2019.08.001 Received 14 May 2019; Received in revised form 9 July 2019; Accepted 2 August 2019 * Corresponding author. E-mail address: faical.brini@cbs.rnrt.tn (F. Brini). Plant Physiology and Biochemistry 142 (2019) 384–394 Available online 02 August 2019 0981-9428/ © 2019 Elsevier Masson SAS. All rights reserved. T