Preiner, Julian Wienkoop, Stefanie Weckwerth, Wolfram Oburger, Eva Table_1_Molecular Mechanisms of Tungsten Toxicity Differ for Glycine max Depending on Nitrogen Regime.docx <p>Tungsten (W) finds increasing application in military, aviation and household appliance industry, opening new paths into the environment. Since W shares certain chemical properties with the essential plant micronutrient molybdenum (Mo), it is proposed to inhibit enzymatic activity of molybdoenzymes [e.g., nitrate reductase (NR)] by replacing the Mo-ion bound to the co-factor. Recent studies suggest that W, much like other heavy metals, also exerts toxicity on its own. To create a comprehensive picture of tungsten stress, this study investigated the effects of W on growth and metabolism of soybean (Glycine max), depending on plant nitrogen regime [nitrate fed (N fed) vs. symbiotic N<sub>2</sub> fixation (N fix)] by combining plant physiological data (biomass production, starch and nutrient content, N<sub>2</sub> fixation, nitrate reductase activity) with root and nodule proteome data. Irrespective of N regime, NR activity and total N decreased with increasing W concentrations. Nodulation and therefore also N<sub>2</sub> fixation strongly declined at high W concentrations, particularly in N fix plants. However, N<sub>2</sub> fixation rate (g N fixed g<sup>−1</sup> nodule dwt) remained unaffected by increasing W concentrations. Proteomic analysis revealed a strong decline in leghemoglobin and nitrogenase precursor levels (NifD), as well as an increase in abundance of proteins involved in secondary metabolism in N fix nodules. Taken together this indicates that, in contrast to the reported direct inhibition of NR, N<sub>2</sub> fixation appears to be indirectly inhibited by a decrease in nitrogenase synthesis due to W induced changes in nodule oxygen levels of N fix plants. Besides N metabolism, plants exhibited a strong reduction of shoot (both N regimes) and root (N fed only) biomass, an imbalance in nutrient levels and a failure of carbon metabolic pathways accompanied by an accumulation of starch at high tungsten concentrations, independent of N-regime. Proteomic data (available via ProteomeXchange with identifier PXD010877) demonstrated that the response to high W concentrations was independent of nodule functionality and dominated by several peroxidases and other general stress related proteins. Based on an evaluation of several W responsive proteotypic peptides, we identified a set of protein markers of W stress and possible targets for improved stress tolerance.</p> glycine max;tungsten toxicity;N-assimilation;nitrate reductase;15N natural abundance;symbiotic N2 fixation;starch accumulation 2019-04-02
    https://frontiersin.figshare.com/articles/dataset/Table_1_Molecular_Mechanisms_of_Tungsten_Toxicity_Differ_for_Glycine_max_Depending_on_Nitrogen_Regime_docx/7937711
10.3389/fpls.2019.00367.s005