Abstract
Lipidomics is an emerging technology, which aims at the global characterization and quantification of lipids within biological matrices including biofluids, cells, whole organs and tissues. The changes in individual lipid molecular species in stress treated plant species and different cultivars can indicate the functions of genes affecting lipid metabolism or lipid signaling. Mass spectrometry–based lipid profiling has been used to track the changes of lipid levels and related metabolites in response to salinity stress. We have developed a comprehensive lipidomics platform for the identification and direct qualification and/or quantification of individual lipid species, including oxidized lipids, which enables a more systematic investigation of peroxidation of individual lipid species in barley roots under salinity stress. This new lipidomics approach has improved with an advantage of analyzing the composition of acyl chains at the molecular level, which facilitates to profile precisely the 18:3-containing diacyl-glycerophosphates and allowed individual comparison of lipids across varieties. Our findings revealed a general decrease in most of the galactolipids in plastid membranes, and an increase of glycerophospholipids and acylated steryl glycosides, which indicate that plastidial and extraplastidial membranes in barley roots ubiquitously tend to form a hexagonal II (HII) phase under salinity stress. In addition, salt-tolerant and salt-sensitive cultivars showed contrasting changes in the levels of oxidized membrane lipids. These results support the hypothesis that salt-induced oxidative damage to membrane lipids can be used as an indication of salt stress tolerance in barley.
Highlights
Plants have evolved complex strategies to cope with salinity stress, including the compartmentation and exclusion of Na+ and Cl−, biosynthesis of compatible solutes, and maintenance of membrane integrity and fluidity by lipid rearrangement (Allakhverdiev et al, 1999; Wu et al, 2005; Salama et al, 2007; Upchurch, 2008; Sarabia et al, 2018)
We present a high-throughput and highsensitivity mass spectrometry–based lipidomics platform for comprehensive characterization of membrane lipid responses that captures a range of oxidized lipids
As roots are the primary site of salt contact, the ability of roots to maintain Fresh weight (FW)/ dry weight (DW) was shown to be an important indicator of the degree of salinity tolerance (Cao et al, 2017)
Summary
Plants have evolved complex strategies to cope with salinity stress, including the compartmentation and exclusion of Na+ and Cl−, biosynthesis of compatible solutes, and maintenance of membrane integrity and fluidity by lipid rearrangement (Allakhverdiev et al, 1999; Wu et al, 2005; Salama et al, 2007; Upchurch, 2008; Sarabia et al, 2018). Lipidomics has emerged as an effective tool to understand the diversity of membrane lipid compositions and unravel the roles of lipids in plant adaptation and tolerance to abiotic stresses (Welti et al, 2007; Natera et al, 2016; Tenenboim et al, 2016) Lipids and their related metabolites can be readily detected from cultured cells or tissue extracts, identified and quantified on a large scale with high sensitivity using the latest techniques in lipidomics (Horn and Chapman, 2012; Köfeler et al, 2012; Haslam and Feussner, 2017; Yu et al, 2018). To maintain the stable structure of chloroplast or plastidic membranes in saline environments, plants alter their monogalactosyl diacylglycerol (MGDG) to digalactosyl diacylglycerol (DGDG) ratios; this alteration is associated with a membrane phase transition between bilayer phases and other less mobile non-bilayer phases (De Vries et al, 2004; Narayanan et al, 2016)
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