Gene Expression Analysis of Prunus persica Fruits During Chilling Injury

Peaches are sensitive to low temperature during refrigerated storage. Preconditioning is a thermal treatment that consists in maintaining stone fruits immediately after harvest and prior to cold storage at 20 °C for 24 h in special chambers. This treatment is aimed to extend fruit market life by reducing chilling injury (CI) symptoms. In this work, cv. ‘Elegant lady’ fruits exposed to preaconditioning treatment showed a severe reduction of the symptoms of CI after 21 days of cold storage (4 ºC). Also, the antioxidant capacity of messocarp tissue, quantified by trolox equivalents, turned out to be lower in preaconditionated fruits when compared against non preaconditionated (control) fruits with chilling injury symptoms. In experiments of RT-qPCR, the relative mRNA abundance of CuZnSOD, catalase and glutathione reductase was significantly greater in control CI fruits, suggesting that at the transcriptional level, cold storage in CI fruits increased the expression of genes associated with the metabolism of reactive oxygen species. To unravel the molecular changes underlying this phenomenon a large-scale transcriptome analysis has been conducted using mPEACH1.0 microarrays. Our analysis indicate an increase in the expression of genes related to redox metabolism in control chilling injury fruits, whereas in preacondionated normal fruits, there is a trend toward the activation of genes related to cell wall metabolism. We will discuss the involvement of these genes in previously characterized metabolic pathways.