Lipid composition remodeling and storage lipid conversion play a critical role in salt tolerance in alfalfa (Medicago sativa L.) leaves

Elucidation of Physiological, Transcriptomic and Metabolomic Salinity Response Mechanisms in Medicago sativa

“…Conversely, a gene encoding an omega-6 fatty acid desaturase, which is known to be involved in the synthesis of 18:2 fatty acids [124], was highly up-regulated under salinity stress (File S1). This latter finding correlates well with previous studies in which the expression of the omega-6 fatty acid desaturase FAD2 was up-regulated under salinity stress in alfalfa leaves [36], and the suggestion that fatty acid desaturation by FADs may provide an important adaptive mechanism to deal with salt stress in alfalfa through the effect of polyunsaturated fatty acid levels on membrane fluidity [125]. Numerous genes involved in lipid degradation were also differentially expressed following salinity treatment, including the up-regulation of a gene encoding a protein with phospholipase D activity (File S2).…”

“…In addition, alterations in the expression of genes involved in other lipid-related pathways, as well as the levels of various lipid metabolites, were also evident in alfalfa leaves following salinity stress ( Figure 5 a and Figure 6 b, File S3 ). Such changes could potentially be involved in the remodeling of membrane lipids under salinity, which has previously been found to occur in plant species, including alfalfa [ 36 , 122 ]. In the current study, a gene encoding a choline kinase, which is involved in phosphatidylcholine biosynthesis and has been found previously to be up-regulated under high salt conditions in Arabidopsis [ 123 ], was down-regulated under salinity stress in alfalfa leaves ( File S2 ), which could lead to an associated reduction in membrane integrity.…”

“…Numerous genes involved in lipid degradation were also differentially expressed following salinity treatment, including the up-regulation of a gene encoding a protein with phospholipase D activity ( File S2 ). Interestingly, phospholipase D proteins, which regulate the production of the important signaling lipid phosphatidic acid, have also been shown to function in salinity stress response in plants [ 126 ] and tend to be up-regulated under this type of stress [ 36 ]. However, their precise role in salinity stress response and/or tolerance remains to be determined.…”

“…While these studies have provided considerable insight into responses related to the first phase of salinity response, where roots are the first point of exposure, far less is known regarding longer-term responses in aboveground tissues, which are also known to provide important adaptive mechanisms for withstanding this type of stress [ 30 ]. Furthermore, although metabolomic analyses are beginning to contribute to the unraveling of salinity response in other plant species in recent years [ 31 , 32 , 33 ], only a very small number of metabolomic assessments of alfalfa have been conducted under salinity stress to date, and these were limited to metabolites targeted to a specific selection of pathways [ 34 , 35 ] or lipidomic profiles [ 36 ]. Therefore, as a means of furthering our understanding of salinity response mechanisms in alfalfa, we sought to assess the physiological responses of M. sativa cv.…”

Identification of genes associated with abiotic stress tolerance in sweetpotato using weighted gene co‐expression network analysis

“…Corroborating our results, Qin, Lin, et al ( 2020 ) observed a slight decrease of glycerolipids due to heat acclimation. Salt stress has also been reported to induce changes in membrane lipids of plants not only growing in maritime sands and salts marshes like the Mesembryanthemum crystallinum (Guo et al, 2022 ) but also in cultivated plants such as maize (Xu et al, 2021 ), sorghum ( Ge et al, 2022 ), wheat, and alfafa (Li et al, 2023 ). The changes include the alterations of the lipid content, their fatty acid components, bilayer to non‐bilayer lipid ratio, and the activities of signaling lipids possibly regulating the membrane fluidity and permeability (Ge et al, 2022 ; Guo et al, 2022 ; Xu et al, 2021 ) A reduction in lipid content under salt stress was observed in salt sensitive barley compared to salt tolerant variety (Chalbi et al, 2013 ).…”