Also, poplar is suitable for genetic transformation and can be propagated vegetatively, facilitating large-scale production of clones. As demand for renewable bioenergy is increasing, poplar, a fast growing pioneer tree, is receiving great amounts of attention due to its suitability for heat and power generation. This demand implies more future scientific and economical interest in using poplar for analyzing stress responses in woody plant species. Moreover, while knowledge of S-nitrosylated proteins in herbaceous model plants is broad, there is limited information regarding woody plants. In the present study we aimed to identify S-nitrosylated proteins in grey poplar to improve understanding of the initial steps in plants�� ozone response. By performing a biotin switch assay in conjunction with quantitative LC-MS/ MS analysis, we tried to answer the following questions: Firstly, are there proteins that are constitutively S-nitrosylated in the green tissue of poplar? Secondly, does acute oxidative stress induce quantitative and/or qualitative alterations in the pattern of S-nitrosylated proteins in the leaves? And finally, if there are changes upon oxidative stress, can we deduce a regulation Vitamin C scheme that may explain the physiological relevance of S-nitrosylation signaling during plant ozone response? Here we report a list of constitutively S-nitrosylated proteins in grey poplar under unstressed conditions. The list comprises many proteins not reported in the context of S-nitrosylation so far. Quantitative analysis revealed significant and rapid changes in the S-nitroso-proteome of poplar undergoing acute ozone exposure. Plant responses to ozone are closely linked to the effective dose taken up by the plant via the stomata. Thus, Loxapine Succinate flux-based indices that take into account ozone deposition into the leaf are considered a more reliable indicator of potential ozone damage than exposure time and air ozone concentration. This study represents the investigation of protein S-nitrosylation patterns in the woody model plant grey poplar. By performing a biotin switch assay optimized for poplar in conjunction with the quantitative LC-MS/MS analysis, we identified 172 proteins that are S-nitrosylated in vivo in callus tissue and fully developed poplar leaves under unstressed conditions and that appear after a short pulse of oxidative stress.