Metabolomics Response to Drought Stress in Argania Spinosa L. Skeels Ecotypes

Argan ( Argania spinosa L.), an endemic specie of Morocco, is vulnerable to future climate change because it is predominantly grown in arid and semi-arid areas. Metabolomic fluctuations under drought stress conditions are mostly unknown in Argan tree. Therefore, we investigate the first report of the metabolic responses of four contrasting Argan ecotypes (Lkhssas, Awlouz, Rbai and Admin) that were subjected to drought stress for 45 days. Using gas chromatography–mass spectrometry, we identified 229 metabolites, including fatty acids, prenol lipids, alkanes, alkenes, steroids and others. Among these, we focused on 21 metabolites which belong mainly to fatty acids and are common to the four Argan ecotype. In stressed plants, “Lkhssas” ecotype shows the high level of Saturated Fatty Acid and Unsaturated Fatty Acid contents. Results revealed that alpha-linolenic acid is the most abundant Fatty Acids in leaves of all contrasting ecotypes. Interestingly, their concentration increased significantly under stress, especially in “Lkhssas” ranging from 25.4% Drought Stress (DS) to 70.1% Control (CK) of total lipids. The second most abundant Fatty Acids were Stearic acid and Palmitic acid, which showed a significant change of their concentration respectively in “Awlouz” and “Lkhssas”. Indeed, the differential metabolites pathway map indicates that some essential metabolites were significantly implicated in the drought stress response.The findings of this study provided new insights into the metabolic responses of Argan tree in drought stress conditions, and served as a base for future studies on transcriptomic and proteomic to enhance the drought tolerance of forest trees.