Proteomic analysis of core breakdown disorder in Conference pears (Pyrus communis L.)

2-DE was applied to study core breakdown disorder in controlled atmosphere stored 'Conference' pears. This physiological disorder is characterized by internal browning of the fruit tissue and the development of cavities. Suitable protein phenol extraction/ammonium acetate-methanol precipitation and 2-DE protocols for a wide pH range were established for pear tissue. The protein expression profiles of healthy, sound (intact tissue of pears with core breakdown) and brown tissue were analyzed with the univariate non-parametric Kolmogorov-Smirnov test and multivariate statistical techniques such as principal component analysis and partial least square discriminant analysis. Both statistical approaches revealed interesting differentially expressed proteins between healthy and disordered pears. LC-ESI-MS/MS identification of differentially expressed proteins between healthy and sound tissue revealed their participation in the energy metabolism, the antioxidant system and ethylene biosynthesis. Up-regulated characteristic proteins in brown tissue were mainly involved in energy metabolism and defense mechanisms. Proteomics coupled to univariate and multivariate statistical techniques seems to be an efficient approach to get a better insight into the different mechanisms and pathways leading to the core breakdown disorder.