Tungsten stress response of soy bean (glycine max), LC-MSMS

ABSTRACT: The transition metal tungsten (W) finds increasing application in military, aviation and household appliance industry, opening new paths for the heavy metal into the environment. Since tungsten shares certain chemical properties with the essential plant micro nutrient molybdenum, it is proposed to inhibit enzymatic activity of molybdoenzymes by replacing the Mo-ion bound to the co-factor. However, recent studies suggest the inhibition of enzymatic activity might not be the only effect W has on plants and that, much like other heavy metals, tungsten exerts toxicity on its own. Still, our understanding of the mechanisms behind the apparent phytotoxicity remains limited.This study investigates the effects of W on growth, nutrient levels (ionome, ICP-MS), starch levels and nitrogen nutrition (IRMS, enzyme activity assays) as well as root and nodule proteome (LC-MS/MS) of Glycine max cv. Primus. Plants were inoculated with Bradyrhizobium japonicum and grown in a semi hydroponic set up using three different tungsten concentrations (zero, 0.1 mM and 0.5 mM). To identify possible benefits of a functional bacterial symbiosis on W induced stress response, two different environmental growth conditions, one with suppressed N-fixation, supplied with Nitrate (10 mM KNO3) and one solely relying on symbiotic N-fixation (zero KNO3), were applied. Glycine max was able to take up considerable amounts of W (703 ± 136 mg kg-1). However, high W resulted in a strong reduction of shoot biomass of both N regimes and of root biomass (N fed only). Irrespective of N regime, NR activity and total N decreased with increasing W concentrations. Similarly, nitrogenase precursor levels as well as N2-fixation, nodule fixation activity (mg N g-1 nodule dry weight) and nodulation were reduced, indicating that nitrogenase synthesis and activity were negatively affected by W stress. However, along a N fix nodule specific induction of the secondary and phytohormone metabolism, it appears that N2 fixation of remaining nodules was not as severely affected by increasing levels of tungsten than nitrate reduction. Besides N metabolism, plants exhibited an imbalance in nutrient and a failure of carbon metabolic pathways accompanied by an accumulation of starch at high tungsten concentrations, independent of N-regime. Proteomic data demonstrated that the response to high W concentrations is 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.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Bradyrhizobium Japonicum Glycine Max

TISSUE(S): Root Nodule, Root

SUBMITTER: Julian Preiner  

LAB HEAD: Stefanie Wienkoop

PROVIDER: PXD010877 | Pride | 2019-04-09

REPOSITORIES: Pride