Lipids are the main constituents of the cell membrane and maintain its fluidity. Plants undergo various changes in lipids under environmental stresses and alter the membrane fluidity and permeability. Membrane lipids mostly contain a polar or neutral head group and fatty acid tails that vary in length and degree of unsaturation. The composition of membrane affects its physicochemical properties and ability to tolerate stress. The moss Physcomitrium patens is an early land plant with unique ability to tolerate stressors like cold and dehydration. During its life cycle, for the most part, mosses remain as gametophytes, multiplying asexually. The period from germination of spores into filamentous protonema, which give rise to gametophyte is transient. They enter reproductive sporophytes stage only under cold temperatures. Because of the diverse roles of these developmental stages and the time span they are exposed to the environment, we hypothesized that these stages share distinct lipid content and composition. To this extent, using LC-MS/MS methods we carried out lipidomic analyses of five developmental stages of the moss. We identified and quantified the major and minor lipid classes (types) and their acyl composition of protonema, early, mid and late gametophyte and sporophyte tissues. Galactolipids, which typically occur in the plastid were predominant in green tissues and thus most abundant in the vegetative tissues but not in sporophytes. Throughout the life cycle, among the phospholipids, phosphatidylcholine was the abundant lipid, a feature that is typical of plant membranes. Sporophyte tissues, however, were distinct from gametophyte and protonema and also other vascular plants with high amounts of phosphatidic acid (PA). In plants, PA typically accumulates in response to stress; it is likely that the low temperature cue necessary for sporophyte formation is associated with spike in PA and needs further investigation. In comparing the acyl composition of the various lipid classes, we identified that in addition to 34C and 36C lipids, moss lipids also contain 38C and 40C, which are not represented in vascular plants. We predict that the occurrence of long-chain, highly unsaturated lipids might contribute to the dynamic nature of the membrane and stability under stress. This study serves as a primary resource to further investigate the role of specific lipids and acyl groups in maintaining membrane properties. Overall, it aids to our understanding of the evolution of stress tolerance in early land plants that coped through harsh environmental conditions during their transition from water to land.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:asrf-1784 |
| Date | 18 March 2021 |
| Creators | Gautam, Deepshila, Kilaru, Aruna |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | Appalachian Student Research Forum |
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