title: Proteomic analysis of peach fruit mesocarp softening and chilling injury using difference gel electrophoresis (DIGE).
abstract: BACKGROUND
  Peach fruit undergoes a rapid softening process that involves a number of metabolic changes. Storing fruit at low temperatures has been widely used to extend its postharvest life. However, this leads to undesired changes, such as mealiness and browning, which affect the quality of the fruit. In this study, a 2-D DIGE approach was designed to screen for differentially accumulated proteins in peach fruit during normal softening as well as under conditions that led to fruit chilling injury.
  
  
  RESULTS
  The analysis allowed us to identify 43 spots -representing about 18% of the total number analyzed- that show statistically significant changes. Thirty-nine of the proteins could be identified by mass spectrometry. Some of the proteins that changed during postharvest had been related to peach fruit ripening and cold stress in the past. However, we identified other proteins that had not been linked to these processes. A graphical display of the relationship between the differentially accumulated proteins was obtained using pairwise average-linkage cluster analysis and principal component analysis. Proteins such as endopolygalacturonase, catalase, NADP-dependent isocitrate dehydrogenase, pectin methylesterase and dehydrins were found to be very important for distinguishing between healthy and chill injured fruit. A categorization of the differentially accumulated proteins was performed using Gene Ontology annotation. The results showed that the 'response to stress', 'cellular homeostasis', 'metabolism of carbohydrates' and 'amino acid metabolism' biological processes were affected the most during the postharvest.
  
  
  CONCLUSIONS
  Using a comparative proteomic approach with 2-D DIGE allowed us to identify proteins that showed stage-specific changes in their accumulation pattern. Several proteins that are related to response to stress, cellular homeostasis, cellular component organization and carbohydrate metabolism were detected as being differentially accumulated. Finally, a significant proportion of the proteins identified had not been associated with softening, cold storage or chilling injury-altered fruit before; thus, comparative proteomics has proven to be a valuable tool for understanding fruit softening and postharvest.
authors.affiliation: Centro de Biotecnología Vegetal, Universidad Andrés Bello, Santiago, Chile.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Nilo
authors.forename: Carlos
authors.initials: C
authors.lastname: Saffie
authors.forename: Kathryn
authors.initials: K
authors.lastname: Lilley
authors.forename: Ricardo
authors.initials: R
authors.lastname: Baeza-Yates
authors.forename: Verónica
authors.initials: V
authors.lastname: Cambiazo
authors.forename: Reinaldo
authors.initials: R
authors.lastname: Campos-Vargas
authors.forename: Mauricio
authors.initials: M
authors.lastname: González
authors.forename: Lee A
authors.initials: LA
authors.lastname: Meisel
authors.forename: Julio
authors.initials: J
authors.lastname: Retamales
authors.forename: Herman
authors.initials: H
authors.lastname: Silva
authors.forename: Ariel
authors.initials: A
authors.lastname: Orellana
mesh_terms: D002853:Chromatography, Liquid; D016000:Cluster Analysis; D003080:Cold Temperature; D015180:Electrophoresis, Gel, Two-Dimensional; D005638:Fruit / Q000235:genetics / Q000378:metabolism*; D015999:Multivariate Analysis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D025341:Principal Component Analysis; D040901:Proteomics / Q000379:methods*; D027861:Prunus / Q000235:genetics / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D010940:Plant Proteins