Quantitative proteomics and metabolomics of the hybrid Eucalyptus grandis x E. camaldulensis, tolerant and susceptible to drought stressThe E. grandis x E. camaldulensis has favourable characteristics of adaptation to drought, conferred by E. camaldulensis and quality of wood for pulp and paper, conferred by E. grandis. This adaptation to drought is related to physiological factors and also expressed in their molecular proteome and metabolome, which change in the presence of stress. The aim of this work was to study the physiological responses, proteomics and metabolomics (primary metabolites) differentially expressed in leaves of Eucalyptus under drought. Two genotypes of E. grandis x E. camaldulensis, a tolerant (T) and a susceptible (S) to drought stress, were subjected to 100% and 30% of field capacity (FC), for the well-watered plants and drought stressed plants, respectively. The treatments were called T100, T30, S100 and S30 for different genotypes, T and S, submitted to different FC, 100% and 30%. These plants were evaluated physiologically using the Infrared Gas Analyzer (IRGA). Labelfree and shotgun quantitative proteomics were realized using UPLC-MS E . The metabolomics study was carried out using GC x GC-TOF/MS mass spectrometer. The proteomics data were processed using the Protein Lynx Global Server program (PLGS) and ExpressionE program, through comparative analyses S100 vs S30 and T100 vs S30, and primary metabolites in ChromaTOF and MetaboAnalyst programs. It was observed that T100 had lower photosynthetic rate and stomatal conductance than S100. Both genotypes showed stomatal conductance and photosynthetic rates lower at 30% of FC than at 100% of FC. The proteomic analysis identified a total of 397, 305, 366, 309 proteins in the treatments S100, S30, T100 and T30 respectively. Comparative PLGS analyses showed an increase in the number of differentially expressed proteins under drought stress. The five biological processes that showed an increase in the number of differentially expressed proteins under drought stress were: cellular homeostasis, photosynthesis, response to abiotic stimulus, response to stress and cell death. The three biological pathways that had the participation of many identified enzymes, which are related to photosynthetic processes, were: carbon fixation in photosynthetic organisms, TCA cycle and glycolysis / gluconeogenesis. The drought reduced the number of differentially expressed proteins related to the metabolism of compounds containing nuclear bases, biological regulation and biosynthetic process, which were related to growth, development and maintenance of the vital processes of plants. The metabolomic analysis identified a total of 93, 94, 90 and 91 primary metabolites in the treatments S100, S30, T100 and T30, respectively. Using Metaboanalyst program, it was possible to identify 15 metabolites that contributed to the separation of treatments with higher "VIP scores", some of these are responsive to drought. The purine and arginine pathway was identified as t...
