Proteins involved in biotic and abiotic stress responses as the most significant biomarkers in the ripening of Pinot Noir skins

We propose an integrated approach, obtained by the combination of multivariate statistics and proteomics, useful to isolate candidate biomarkers for the evaluation of
grape ripening. We carried out a comparative 2-DE analysis of grape skins collected in three moments of ripening and analyzed the spot volume dataset through the application of principal component analysis followed by forward stepwiselinear discriminant analysis. This technique allowed to
discriminate véraison, quite mature and mature samples,
and to sort the matched spots according to their significance.
We identified 36 spots showing high discriminating coefficients
through liquid chromatography - electrospray ionization
- tandem mass spectrometry (LC-ESI-MS/MS). Most
of them were involved in biotic and abiotic stress responses
indicating these enzymes as good candidate markers of berry
ripening. These evidences hint at a likely developmental role
of these proteins, in addition to their reported activity in
stress events. Restricting the same statistical analysis to the
samples belonging to the two last stages, it was indicated that
this approach can clearly distinguish these close and similar
phases of berry development. Taken all together, these
results bear out that the employment of the combination of
2-DE and multivariate statistics is a reliable tool in the
identification of new protein markers for describing the
ripening phases and to assess the overall quality of the fruit.