Plant Metabolic Networks Under Stress: a Multi-species/Stress Condition Meta-analysis

Plant stress acclimation depends on metabolic changes. However, the knowledge concerning the modularity and robustness of plant metabolic networks under stress conditions remains fragmented. Here we carried out a multi-species/stress condition meta-analysis using previously published metabolite profiling data from plants under water deficit, cold, salt and nitrogen deprivation stress conditions. We carried out extensive network and multivariate analyses aiming to identify stress biomarkers and to investigate how plant metabolic network is altered in terms of topology and connectivity by stress conditions. Partial least squares discriminant analysis (PLS-DA) was effective in differentiating stressed from non-stressed plants at a metabolic level. However, no general pattern in both density and heterogeneity of the metabolic network was observed after stress imposition. Integrative analysis identified metabolic markers for multiple stresses in plants, including asparagine, shikimate, fructose and raffinose. This analysis further highlights that amino acid metabolism is a major hub for plant stress acclimation. This idea is supported by the fact that several amino acids related to photorespiration and that are used as substrates for alternative plant respiration pathways or the synthesis of secondary metabolites were found as key for the structure and modulation of the network under stress. Our results collectively suggest that stress-induced changes in metabolic network topology are species/stress level–specific. However, several hubs related to amino acid metabolism emerge as key nodes in the network when plants are subjected to stress conditions, highlighting that our approach can be used by systems-driven plant breeding programs toward plant stress tolerance improvement.