Characterization of the metabolic profile of native species of Atlantic Forest exposed to environmental stressors

Abstract

Forest ecosystems are subjected to several natural and anthropic stressors, such as extreme weather conditions and high atmospheric concentrations of ozone and nitrogen compounds, due to increasing use and occupation of the soil by human populations. These environmental stressors can cause the increase of reactive oxygen species (RosOS), which will start multiple oxidation events causing damage, from the cellular level to the ecosystem. The intensity of these damages depends on how efficient is the mobilization of antioxidant defenses to maintain the pro-oxidant/antioxidant balance. Enzymes and substances from the primary and secondary metabolism, as for example, phenolics and carbohydrates are among the compounds with antioxidant properties. Changes in the content and chemical composition of these compounds that indicate oxidative stress are tools for evaluating the potential tolerance of plant species to the stress imposed by the environmental stressors. In this project, an ecosystem approach will be adopted, by means of analysing the metabolic profile of native species from the Atlantic Forest, with similar ecological functions in areas potentially impacted by environmental stressors (pioneer/non-pioneer species and lianas). We aim at enlarging the knowledge about variations in foliar composition of phenolic compounds, carbohydrates, amino acids and polyols in tree species of remnants of Atlantic forest, in the State of São Paulo and Minas Gerais, belonging to different functional groups (pioneer/early secondary and late secondary trees) in response to environmental stressors inductors of oxidative stress and thereby infer about their ability to tolerate it. Still, we intend to establish dose x response curves between the changes in the content and composition of primary and secondary metabolism compounds and environmental stressors relevant to the region of study (solar radiation, nitrogen compounds and ozone). The project will be developed in three steps: the first will be conducted under natural conditions, by sampling leaves of pioneer and non-pioneer tree species of remnants of Atlantic forest, in two distinct seasons of the year; the second step will be conducted in a FACE (Free-Air Controlled Exposure) system, installed at the Institute of Sustainable Plant Protection/National Council of Research (IPSP/CNR), in Florence/Italy, in collaboration with Dr. Elena Paoletti, aiming to model the responses of a tree species and a liana species to the oxidative stress induced by ozone. The third and final step will be held in the same FACE system, by cultivating the same liana species in pots containing standardized substrate, which will be subjected to excess of nitrogen in the soil and/or to ozone, in order to test the combined effect combined of urban pollutants in the metabolic profile of this species. At the end of each experimental step, leaf samples will be analysed for determining the composition and content of primary and secondary plant metabolites by using GC/MS and HPLC-DAD-MS. (AU)