Evaluation of proteome alterations induced by cadmium stress in sunflower (Helianthus annuus L.) cultures

• A comparative proteomic approach is highlithed for evaluating sulflower growth under Cd stress.
• A phenol-based extraction allows a good gel resolution.
• The presence of higher amount of Cd causes imbalance in the protein production to the plants.
• Interaction between differential proteins is dicussed.
• Those most affected biological process by Cd are identified.

The present study evaluates, at a proteomic level, changes in protein abundance in sunflower leaves in the absence or presence (at 50 or 700 mg) of cadmium (as CdCl2). At the end of the cultivation period (45 days), proteins are extracted from leaves with phenol, separated by two-dimensional difference gel electrophoresis (2-D DIGE), and excised from the gels. The differential protein abundances (for proteins differing by more than 1.8 fold, which corresponds to 90% variation) are characterized using nESI-LC–MS/MS. The protein content decreases by approximately 41% in plants treated with 700 mg Cd compared with control plants. By comparing all groups of plants evaluated in this study (Control vs. Cd-lower, Control vs. Cd-higher and Cd-lower vs. Cd-higher), 39 proteins are found differential and 18 accurately identified; the control vs. Cd-higher treatment is that presenting the most differential proteins. From identified proteins, those involved in energy and disease/defense (including stress), are the ribulose bisphosphate carboxylase large chain, transketolase, and heat shock proteins are the most differential abundant proteins. Thus, at the present study, photosynthesis is the main process affected by Cd in sunflowers, although these plants are highly tolerant to Cd.

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