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Under global climate change forecasts, the pressure of environmental stressors (and in particular drought) on crop productivity is expected to rise and challenge further global food security. The application of beneficial microorganisms may represent an environment friendly tool to secure improved crop performance and yield stability. Accordingly, this current study aimed at elucidating the metabolomic responses triggered by mycorrhizal (Funneliformis mosseae) inoculation of durum (Triticum durum Desf.; cv. ‘Mongibello’) and bread wheat cultivars (Triticum aestivum L.; cv. ‘Chinese Spring’) under full irrigation and water deficit regimes. Metabolomics indicated a similar regulation of secondary metabolism in both bread and durum wheat cultivars following water limiting conditions. Nonetheless, a mycorrhizal fungi (AMF) x cultivar interaction could be observed, with the bread wheat cultivar being more affected by arbuscular colonization under water limiting conditions. Discriminant compounds could be mostly related to sugars and lipids, both being positively modulated by AMF colonization under water stress. Moreover, a regulation of metabolites related to oxidative stress and a tuning of crosstalk between phytohormones were also evidenced. Among the latter, the stimulation of the brassinosteroids biosynthetic pathway was particularly evident in inoculated wheat roots, supporting the hypothesis of their involvement in enhancing plant response to water stress and modulation of oxidative stress conditions. This study proposes new insights on the modulation of the tripartite interaction plant-AMF-environmental stress.

Salinity is among the most detrimental and diffuse environmental stresses. Halophytes are plants that developed the ability to complete their life cycle under high salinity. In this work, a mass spectrometric metabolomic approach was applied to comparatively investigate the secondary metabolism processes involved in tolerance to salinity in three halophytes, namely S. brachiata, S. maritima and S. portulacastrum. Regarding osmolytes, the level of proline was increased with NaCl concentration in S. portulacastrum and roots of S. maritima, whereas glycine betaine and polyols were accumulated in S. maritima and S. brachiata. Important differences between species were also found regarding oxidative stress balance. In S. brachiata, the amount of flavonoids and other phenolic compounds increased in presence of NaCl, whereas these metabolites were down regulated in S. portulacastrum, who accumulated carotenoids. Furthermore, distinct impairment of membrane lipids, hormones, alkaloids and terpenes was observed in our species under salinity. Finally, several other nitrogen containing compounds were involved in response to salinity, including amino acids, serotonin and polyamine conjugates. In conclusion, metabolomics highlighted that the specific mechanism each species adopted to achieve acclimation to salinity differed in the three halophytes considered, although response osmotic stress and oxidative imbalance have been confirmed as the key processes underlying NaCl tolerance.

Ultraviolet-B (UV–B) radiation impacts the plant behaviour in many ways, including modifying their secondary metabolism. Although several studies have quantified the UV-B effects on phenolic composition, most of them focused on leaves or investigated a limited amount of phenolics. The present work aimed to investigate the phenolic changes after two postharvest UV-B treatments, 10 and 60 min (1.39 kJ m−2 and 8.33 kJ m−2, respectively), on peach (Prunus persica cv Fairtime) fruit with a non-targeted, whole profiling approach, and targeted gene expression analysis on skin. After both UV-B exposures, peach fruit were harvested at 24 and 36 h for “phenol-omics” analysis, while additional 6 h and 12 h recovery times were used for gene expression analysis. Our results revealed that both UV-B exposures resulted in a decrease of several phenolic compounds, such as anthocyanins, after 24 h from the exposure. In contrast, the expression of the UV-B signalling components, the phenylpropanoid biosynthesis genes and their transcriptional regulators increased 6 h after the treatment, mostly with a UV-B-dose dependent behaviour, preceding an accumulation of most phenolics in both the UV-B treatments at 36 h compared to 24 h. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed that flavonoids, particularly anthocyanins, were the main phenolic subclasses accumulated after UV-B exposure.