Reduction of enzymatic browning of fresh-cut guava fruit by exogenous hydrogen peroxide-activated peroxiredoxin/thioredoxin system

Abiotic stresses in plants are commonly caused by antioxidant system imbalance in their tissues. A peroxiredoxin/thioredoxin (Prx/Trx) system is a ubiquitous antioxidant system involved in sensing and detoxifying hydrogen peroxide (H2O2) and other reactive oxygen species (ROS). This study investigated exogenous H2O2 potential in reducing browning and its interaction with the Prx/Trx system in fresh-cut guava fruit during storage at 25 degrees C. Fresh-cut guava samples were immersed in 0 (control) and 250 mM H2O2 for 10 min, placed on a foam tray, packed inside a polyethylene bag and kept at 25 +/- 1 degrees C for 48 h. The H2O2 treatment reduced browning and maintained fresh-cut guava fruit quality during storage. The H2O2 treatment reduced oxidative membrane damage and an accumulation of ROS, but activated the Prx/Trx system by stimulating the activities of peroxiredoxin and thioredoxin reductase, and NADPH-generating dehydrogenases including glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase as well as an increase in NADP redox state. The altered redox state and the activation of the Prx/Trx system by H2O2 was correlated with delayed browning of fresh-cut guava. Thus, the Prx/Trx system is involved in browning development, and H2O2 treatment could delay browning in fresh-cut guava by reducing oxidative membrane damage via stimulating the Prx/Trx system.