Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Essential oil of peppermint in symbiotic relationship with Piriformospora indica and methyl jasmonate application under saline condition Masoume Khalvandi a, ⁎ , Mohammadreza Amerian a , Hematollah Pirdashti b , Sara Keramati b , Jaber Hosseini c a Department of Agronomy, Faculty of Agriculture, Shahrood University of Technology, Iran b Department of Agronomy, Genetic and Agricultural Biotechnology Institute of Tabarestan, Sari Agricultural Sciences and Natural Resources University, Iran c Department of Agronomy, Faculty of Agriculture, Tarbiat Modares University, Iran ARTICLE INFO Keywords: Essential oil Mycorrhiza-like Methyl jasmonate Salinity Peppermint GC–MS ABSTRACT Peppermint (Mentha piperita L.) is one of the most important medicinal and aromatic plants that its essential oil is extensively used in fragrance, aromatherapy, flavor, and pharmaceutical properties. This study aimed to eval- uate the effects of Piriformospora indica inoculation, methyl jasmonate and salinity effects on essential oil from leaves, total phenol, anthocyanin, reactive oxygen species (ROS)-scavenger activity and composition of the oil in peppermint. Treatments included inoculation, and non-inoculation of P. indica, methyl jasmonate (0 and 75 μM) and four salinity levels of irrigation water (0, 3, 6 and 9 dS m −1 ). Essential oil constituents have been analyzed by GC–MS. The results showed that salinity increased lipid peroxidation as well as membrane electrolyte leakage, while, membrane permeability influenced by methyl jasmonate application, P. indica inoculation and their interaction, reduced the negative effect of salinity on membrane electrolyte leakage. Fungal symbiosis and methyl jasmonate application ameliorated the negative effects of salinity on essential oil content. The results showed that monoterpenes constitute the major components of essential oil. The main oil constituents, menthol, menthone and 1,8-cineole increased considerably in P. indica and methyl jasmonate treatments. The highest 2,2- diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and polyphenol oxidase was observed in the P. indica inoculation, however methyl jasmonate treatment gave the highest content of total phenol and anthocyanin. In general, when inoculated plants were sprayed by methyl jasmonate, antioxidant activity increased and synthesis of medicinal and anti-microbial compounds was observed. 1. Introduction Mentha piperita L. is one of the most important essential oil crops from Lamiaceae family, a perennial herb which found in many regions around the world. The essential oil of peppermint is used as fragrance and cosmetic, food and pharmaceutical (Herro and Jacob, 2010) cyto- toxic, insecticidal, antioxidant and anti-inflammatory compounds (Sun et al., 2014). Also, antifungal and antimicrobial activities of peppermint essential oil have been reported (Moghaddam et al., 2013). It's also been proven that they have phenolic compounds like anthocyanin which play an important role to scavenge reactive oxygen species (ROS) and cancer preventative activities (Miguel, 2011). Several factors, including salt stress affect the function of medicinal plants (Gharib et al., 2014). By increasing the accumulation of toxic NaCl ions in leaves (Giuffrida et al., 2009) and decreasing the absorp- tion of water and mineral nutrients (Parida and Das, 2005), salinity causes physiological changes and biochemical processes which lead to the reduction of essential oil biosynthesis and crop yield losses. There are many reports about the negative effects of salt stress on secondary metabolites, essential oils yield and herb biomass (Rahimi et al., 2012; Gharib et al., 2014: Roodbari et al., 2013). Nowadays researchers use new strategies like symbiotic fungi (Yun et al., 2018) and plant growth regulators (Rezai et al., 2013) to minimize the negative effects of saline water and soil, and to improve growth and increase plant performance. Piriformospora indica, (Basidiomycota) is one of these beneficial en- dophytic fungi that is similar to arbuscular mycorrhiza fungi (Varma et al., 1999) colonizes the roots of many plant species (Rafiqi et al., 2013). It stimulates the immune system of plants (Jacobs et al., 2011) and increases plant resistance to salinity (Waller et al., 2005; Yaghoubian et al., 2014). Symbiosis relationship with P. indica stimu- lates enzymes and physiological activity which improves the growth of the aerial parts and increases the synthesis of secondary metabolites in https://doi.org/10.1016/j.indcrop.2018.10.072 Received 23 June 2018; Received in revised form 21 October 2018; Accepted 23 October 2018 ⁎ Corresponding author. E-mail address: M.khalvandi@gmail.com (M. Khalvandi). Industrial Crops & Products 127 (2019) 195–202 0926-6690/ © 2018 Elsevier B.V. All rights reserved. T