Proteomic Analysis of Grape Berry Cell Cultures Reveals that Developmentally Regulated Ripening Related Processes Can Be Studied Using Cultured Cells

Background: This work describes a proteomics profiling method, optimized and applied to berry cell suspensions to organ-specific cultures as a platform to study grape berry ripening. Variations in berry ripening within a cluster(s) a vine and in a vineyard are a major impediment towards complete understanding of the functional processes that ripening, specifically when a characterized and homogenous sample is required. Berry cell suspensions could some of these problems, but their suitability as a model system for berry development and ripening needs to be first. Methodology/Principal Findings: In this study we report on the proteomic evaluation of the cytosolic proteins obtained synchronized cell suspension cultures that were established from callus lines originating from green, veraison and ripe vinifera berry explants. The proteins were separated using liquid phase IEF in a Microrotofor cell and SDS PAGE. This proved superior to gel-based 2DE. Principal component analysis confirmed that biological and technical repeats tightly and importantly, showed that the proteomes of berry cultures originating from the different growth/stages were distinct. A total of twenty six common bands were selected after band matching between different stages and twenty two of these bands were positively identified. Thirty two % of the identified proteins are currently as hypothetical. The differential expression profile of the identified proteins, when compared with published on grape berry ripening, suggested common trends in terms of relative abundance in the different developmental between real berries and cell suspensions. Conclusions: The advantages of having suspension cultures that accurately mimic specific developmental stages are and could significantly contribute to the study of the intricate regulatory and signaling networks responsible for development and ripening.