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The frequency of combined stress events is increasing due to climate change and represents a new threat to olive (Olea europaea) culture. How olive plants modulate their profile of metabolites under multiple stressing agents remains to unveil, although several metabolites affect plants' resilience, and olive production and quality. Young olive plants were exposed to a water deficit (WD) for 30 days and then exposed to a shock of heat and high UVB-radiation (WDHS+UVB treatment) for 2 days. Then, plants were re-watered and grown under optimal conditions (recovery) for 30 days. Leaves were collected after stress and recovery, analysed by liquid and gas chromatography, and the lipophilic and phenolic profiles were characterized. Except for the oleuropein derivatives, the qualitative metabolite profile was similar during stress and recovery. Metabolite increases or decreases in response to stress were stronger when WD was followed by WDHS+UVB treatment. Phenolic compounds (luteolin-7- O -glucoside, quercetin-3- O -rutinoside, apigenin-7- O -glucoside, chrysoeriol-7- O -glucoside, kaempferol derivatives, oleuropein, and lucidumoside C) were the most involved after WD and WDHS+UVB, possibly acting as reactive oxygen species (ROS) scavengers. Lipophilic compounds were more relevant during the recovery period. The catabolism of fatty acids and carbohydrates may provide the necessary energy for plant performance reestablishment, and sterols, long-chain alkanes, and terpenes metabolic pathways may be shifted for the production of compounds with a more important stress protection role. This work highlights for the first time that tolerance mechanisms activated by WD in olive plants are related to metabolite changes, that are adjusted when other stressors are overlapped (WDHS+UVB), and also help the plants recover. This metabolites' plasticity represents an essential contribution to understanding how dry-farming olive orchards may deal with drought combined with high UV-B or heat. [Display omitted] • WD and WDHS+UVB activate the same metabolite responses. • WDHS+UVB induce a stronger metabolite quantity change. • Polyphenols are the most involved to counteract the stress negative effects. • Lipophilic metabolites are more involved in physiological reestablishment after stress. [ABSTRACT FROM AUTHOR]

• Cobrançosa olives are richer in organic acids, esters and carbohydrates. • C.Serpa olives present higher levels of phenolic compounds. • Stress modulates olives' phenolic/lipophilic contents in a cultivar-dependent way. • C.Serpa olives have higher stress susceptibility than Cobrançosa and C.C.Branco. • Olives can be enriched in bioactive compounds in response to environmental stresses. The awareness of the functional and nutraceutical properties of olives and olive oil bioactive constituents contributed to oliviculture recent increase. Olives' metabolism and nutritional quality are determined by how the olive-tree is coping to climate change-related episodes, which increasingly occur in the Mediterranean. We characterize the most relevant lipophilic and phenolic compounds of olives from Olea europaea cultivars [Cobrançosa, Cordovil de Castelo Branco and Cordovil de Serpa (C.Serpa)] exposed to drought + heat. Olives from the three cultivars presented a similar qualitative profile but differed in their relative richness. Cobrançosa olives are richer in organic acids, esters and carbohydrates, while C.Serpa olives have higher levels of phenolic compounds, particularly under control conditions. Drought + heat changed the quantitative profile of olives, in a way dependent on the cultivar, and C.Serpa olives showed the highest stress susceptibility. Climate change-related conditions stimulate the accumulation of relevant bioactive compounds in olives, contributing to increasing its nutritional value. [ABSTRACT FROM AUTHOR]