Metabolic Responses of Thymus vulgaris to Water Deficit Stress

Background: During plant life, there are several factors affecting plant growth, development and finally their productivity. Water is one of the most important environmental factors, as it is the major constituent of all living organisms. This stress influences plant metabolism both directly and indirectly. Thymus vulgaris or common thyme is well known since ancient times for its medicinal and culinary uses. Its extract has antiseptic, antibacterial and spasmolytic properties. Objective: To optimise the developed general scheme of DI FT-ICR metabolite profiling of plant extracts along with some basic physiological indices in Thymus vulgaris during water deficit stress. Methods: Combined morpho-physiological parameters (including water potential, water content, shoot fresh weight and soil moisture) with metabolite profiling were used during water deficit stress. Nontargeted metabolite profiling was carried out by DI FTICR mass spectrometry. Results: All physiological parameters that significantly changed corresponded to the soil moisture decrease. Likewise, the patterns of metabolite changes indicated by the results of DI FT-ICR reflected the physiological responses. Of 4755 peaks, 65 were selected as the most effective peaks based on their PCA loading scores. The selected peaks followed 3 major patterns over time, which have been described in detail. Major compounds, namely phenylalanine, tryptophan, asparagine, N-Carbamyl-β- Alanin and D-Xylulose-5P were affected under water shortage conditions. Conclusion: We highlighted the important role of these compounds in water deficit stress tolerance via plant hormones, secondary metabolite biosynthesis and purine, pyrimidine and histidine metabolism. Here, the results confirm the application of high-throughput approach DI-FTICR to study water deficit stress responses of thyme.