Untargeted MS-Based Metabolomics Analysis of the Responses to Drought Stress in Quercus ilex L. Leaf Seedlings and the Identification of Putative Compounds Related to Tolerance

The effect and responses to drought stress were analyzed in Quercus ilex L. seedlings using a nontargeted metabolomic approach, implementing the approaches of previous studies which other -omics platforms, transcriptomics, proteomics employed. This work aimed characterize Q. leaf metabolome, determining possible mechanisms molecular markers tolerance identifying putative bioactive compounds. Six-month-old seedling leaves subjected imposed by water withholding under high-temperature irradiance conditions collected when fluorescence decreased 20% (day 17) 45% 24) relative irrigated seedlings. A total 3934 compounds resolved, with 616 being variable 342 identified, belonged five chemical families. Out identified compounds, 33 variable, mostly corresponding amino acids, carboxylic benzenoids, flavonoids isoprenoids. Epigallocatechin, ellagic acid, pulegone, indole-3-acrylic acid dihydrozeatin-O-glucoside up-accumulated at both sampling times. An integrated multi-omics analysis phenolic related enzymes was performed, revealing that some involved flavonoid pathways (chalcone synthase, anthocyanidin synthase reductase) day 24 non-irrigated Some are proposed for assisting breeding programs based on selection elite genotypes.