Pterostilbene-loaded PLGA nanoparticles alter phenylpropanoid and oxylipin metabolism in Solanum lycopersicum L. leaves

Due to the fast-changing global climate, conventional agricultural systems have to deal with more unpredictable and harsh environmental conditions leading to compromise food production. The application of phytonanotechnology can ensure safer and more sustainable crop production, allowing the target-specific delivery of bioactive molecules with great and partially explored positive effects for agriculture, such as an increase in crop production and plant pathogen reduction. In this study, the effect of free pterostilbene (PTB) and poly(lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) loaded with pterostilbene was investigated on Solanum lycopersicum L. metabolism. An untargeted NMR-based metabolomics approach was used to examine primary and secondary metabolism whereas a targeted HPLC-MS/MS-based approach was used to explore the impact on defense response subjected to anti-oxidant effect of PTB, such as free fatty acids, oxylipins and them impact on hormone biosynthesis, in particular salicylic and jasmonic acid. In tomato leaves after treatment with PTB and PLGA NPs loaded with PTB (NPs + PTB), both NPs + PTB and free PTB treatments increased GABA levels in tomato leaves. In addition, a decrease of quercetin-3-glucoside associated with the increase in caffeic acid was observed suggesting a shift in secondary metabolism towards the biosynthesis of phenylpropanoids and other phenolic compounds. An increase of behenic acid (C22:0) and a remodulation of oxylipin metabolism deriving from the linoleic acid (i.e. 9-HpODE, 13-HpODE and 9-oxo-ODE) and linolenic acid (9-HOTrE and 9-oxoOTrE) after treatment with PLGA NPs and PLGA NPs + PTB were also found as a part of mechanisms of plant redox modulation. To the best of our knowledge, this is the first study showing the role of PLGA nanoparticles loaded with pterostilbene in modulating leaf metabolome and physiology in terms of secondary metabolites, fatty acids, oxylipins and hormones. In perspective, PLGA NPs loaded with PTB could be used to reshape the metabolic profile to allow plant to react more quickly to stresses.