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Open Access Highly Accessed Research article

Proteomic analysis of peach fruit mesocarp softening and chilling injury using difference gel electrophoresis (DIGE)

Ricardo Nilo12, Carlos Saffie12, Kathryn Lilley3, Ricardo Baeza-Yates4, Verónica Cambiazo56, Reinaldo Campos-Vargas127, Mauricio González5, Lee A Meisel12, Julio Retamales8, Herman Silva29 and Ariel Orellana12*

Author Affiliations

1 Centro de Biotecnología Vegetal, Universidad Andrés Bello, Santiago, Chile

2 Millennium Nucleus in Plant Cell Biotechnology (MN-PCB), Santiago, Chile

3 Cambridge Centre for Proteomics, University of Cambridge, Cambridge, UK

4 Dept. of Computer Science, Universidad de Chile, Santiago, Chile

5 Laboratorio de Bioinformática y Expresión Génica, INTA-Universidad de Chile, Santiago, Chile

6 Millennium Nucleus Center for Genomics of the Cell (CGC), Santiago, Chile

7 Institute of Agricultural Research (INIA-La Platina), Santiago, Chile

8 Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile

9 Plant Functional Genomics & Bioinformatics Lab, Universidad Andrés Bello, Santiago, Chile

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BMC Genomics 2010, 11:43  doi:10.1186/1471-2164-11-43

Published: 18 January 2010

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.