Indeed, this information would undoubtedly assist plant producers and breeders to gain more yield under stressed conditions. Ĭonsidering the economic and phytotherapeutic importance of this genus, investigation on the impact of environmental stresses, such as water deficit, could be very informative and useful. Rapidly increasing demand for various thyme products indicates the importance of further research on this plant, in order to comprehend the mechanisms involved in plant adaptation to different abiotic/biotic stresses. Thyme itself, a perennial herb, has been well-known worldwide since ancient times for its medicinal and culinary uses, and its extracts possess antiseptic, antibacterial and spasmolytic properties. Thyme belongs to the Thymus genus and the Lamiaceae (Labiatae) family, one of the largest families of dicotyledons rich in aromatic plant species. Such remodeling, finally, maintains lipid dynamics and membrane protein functionality. Moreover, lipids mitigate cell damage through membrane remodeling in response to abiotic stresses. Signaling lipids are quickly synthesized upon stress initiation by a wide range of enzymes including phospholipases, acyl hydrolases, phytosphingosine kinases, diacylglcerol kinases, and fatty acid amide hydrolases. Different groups of lipids are involved in signaling systems, including lysophospholipids, fatty acids, phosphatidic acid, inositol phosphate, diacylglycerols, oxylipins, sphingolipids, and N-acylethanolamine. First, they act as signaling mediators second, they play an important role in the process of alleviating the deleterious effects of stress. Of note, lipids possess two major roles in the organism’s response to stress. Lipids are cell macromolecules with essential structural, energy storage and signaling roles in biological systems. Lipidome changes and membrane lipid remodelling are relevant strategies adopted by plant cells to counteract abiotic stresses such as drought. Īt a metabolic level, sensitive plants usually exhibit a higher number ofsignificantly altered metabolites than tolerant plants, though, qualitatively, the latter show increases in the accumulation of osmolytes (that maintain the cell water status), and antioxidants that protect plant cells from reactive oxygen species (ROS) produced during drought stress.
Therefore, drought stress may largely impact crop yield and quality and, hence, food security. Water deficit is characterized by morphological and physiological features in plants, such as decreased leaf water potential, wilting, stomatal closure, reduced gas exchange and photosynthesis, and, finally, plant death.
In plants, water is involved in a number of pivotal physiological functions, such as plant growth and photosynthesis, and water deficiency results in a severe and often lethal stress in plant cells. It has been estimated that drought, a major type of abiotic stress, affects around 64% of the world’s land area. These factors reduce crop yield and therefore, cause global economic losses. In their environment, plants are often exposed to a plethora of biotic and abiotic stresses, such as drought, salinity, extreme temperatures, nutritional deficiencies, heavy metals, and pollutants, as well as pathogen and insect attacks. The combination of lipid profiling and physiological parameters represented a promising tool for investigating the mechanisms of plant response to drought stress at non-polar metabolome level. Partial least square discriminant analysis separated all the samples into four groups: tolerant watered, tolerant stressed, sensitive watered and sensitive stressed. In tolerant plants, the level of lipids involved in signaling increased, while intensities of those induced by stress (e.g., oxylipins) dramatically decreased (50–60%), in particular with respect to metabolites with m/ z values of 519.3331, 521.3488, and 581.3709. Sensitive plants showed the highest decrease (55%) in main lipid components such as galactolipids and phospholipids. In addition, different trends for a number of non-polar metabolites were observed when comparing stressed and control samples, for both sensitive and tolerant plants. Tolerant and sensitive plants exhibited clearly different responses at a physiological level. Non-targeted non-polar metabolite profiling was carried out using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry with one-month-old plants exposed to drought stress, and their morpho-physiological parameters were also evaluated. The effects of prolonged drought on lipid profile were investigated in tolerant and sensitive thyme plants ( Thymus serpyllum L. Thymus is one of the best known genera within the Labiatae (Lamiaceae) family, with more than 200 species and many medicinal and culinary uses.
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