Differential protein expression assessed by two-dimensional gel electrophoresis for two wheat varieties grown at four nitrogen levels

To limit N-fertilizer applied on wheat, cultivars that use N more efficiently are needed. Our objective was to investigate differences of nitrogen utilization in varieties by studying qualitative and quantitative proteins expression. Two wheat varieties, 'Arche' and 'Récital', were grown under controlled conditions at four N levels (0, 2, 8, and 20 mg N/plant/day) with two replicates. The number of tillers/plant, aerial dry weight/plant and total N content were measured after two months. Two-dimensional gel electrophoresis was also performed on leaf protein extracts. Analyses of variance showed that the N level effect was highly significant for the number of tillers/plant, aerial dry weight and N content. The variety x N level interaction was significant for N content. Analyses of variance on % volume carried out for 524 spots showed a significant variety effect for 55 spots and a significant N treatment effect for 76 spots. Twenty spots showed a significant variety x N treatment interaction. Fourteen proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The possible role of these proteins, eight of which belong to the carbon metabolism, is discussed.