Metabolomic, proteomic and biophysical analyses of Arabidopsis thaliana cells exposed to a caesium stress. Influence of potassium supply.
The incorporation and localisation of 133Cs in a plant cellular model and the metabolic response induced were analysed as a function of external K concentration using a multidisciplinary approach. Sucrose-fed photosynthetic Arabidopsis thaliana suspension cells, grown in a K-containing or K-depleted medium, were submitted to a 1 mM Cs stress. Cell growth, strongly diminished in absence of K, was not influenced by Cs. In contrast, the chlorophyll content, affected by a Cs stress superposed to K depletion, did not vary under the sole K depletion. The uptake of Cs was monitored in vivo using 133Cs NMR spectroscopy while the final K and Cs concentrations were determined using atomic absorption spectrometry. Cs absorption rate and final concentration increased in a K-depleted external medium; in vivo NMR revealed that intracellular Cs was distributed in two kinds of compartment. Synchrotron X-ray fluorescence microscopy indicated that one could be the chloroplasts. In parallel, the cellular response to the Cs stress was analysed using proteomic and metabolic profiling. Proteins up- and down-regulated in response to Cs, in presence of K+ or not, were analysed by 2D gel electrophoresis and identified by mass spectrometry. No salient feature was detected excepting the overexpression of antioxidant enzymes, a common response of Arabidopsis cells stressed whether by Cs or by K-depletion. 13C and 31P NMR analysis of acid extracts showed that the metabolome impact of the Cs stress was also a function of the K nutrition. These analyses suggested that sugar metabolism and glycolytic fluxes were affected in a way depending upon the medium content in K+. Metabolic flux measurements using 13C labelling would be an elegant way to pursue on this line. Using our experimental system, a progressively stronger Cs stress might point out other specific responses elicited by Cs.
Le Lay
P
P
Laboratoire de physiologie cellulaire végétale, UMR 5168 CEA/CNRS/INRA/UJF, DRDC, CEA-Grenoble, avenue des Martyrs, 38054 Grenoble cedex 09, France.
Isaure
M-P
MP
Sarry
J-E
JE
Kuhn
L
L
Fayard
B
B
Le Bail
J-L
JL
Bastien
O
O
Garin
J
J
Roby
C
C
Bourguignon
J
J
D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002586:Cesium / Q000493:pharmacokinetics / Q000633:toxicity*; D002588:Cesium Radioisotopes / Q000493:pharmacokinetics / Q000633:toxicity*; D002734:Chlorophyll / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011188:Potassium / Q000494:pharmacology*; D020543:Proteome
D002588:Cesium Radioisotopes; D020543:Proteome; D002734:Chlorophyll; D002586:Cesium; D011188:Potassium