Biocontrol proteomics: development of an in situ interaction model and a protein extraction method for a proteomic study of the inhibiting mechanisms of Pichia anomala against Botrytis cinerea

The biocontrol by Pichia anomala strain Kh6 (Hansen) Kurtzman (Saccharomycetales: Endomycetaceae) has been extensively studied using microbial, biochemical and molecular approaches. However, due to the complexity of the interaction process, the inhibition mechanism remains uncharacterized. An objective study based on proteomic techniques could allow to increase our knowledge. Studying modes of action requires conditions as close as possible to natural infection in order to take into account interactions between organisms implicating a more complex protein extraction procedure. In the present study, we developed an in situ model allowing the interaction between apple, antagonist and pathogen and maintaining the antagonist inhibitory effect while limiting the contaminations by the apple components. Moreover, we set up an extraction protocol compatible with our in situ conditions and suitable for 2D analysis. Nine protocols, which differed in cell lysis or protein precipitation procedures, were compared on the basis of the protein yield, 1D gel quality and 2D gel quality.