Reactive oxygen species mediate the relationship between mitochondrial function and delayed luminescence during senescence of strawberry (Fragaria ananassa) fruits

Ultra-weak luminescence (UWL) is a ubiquitous luminescence phenomenon in organisms that is involved in oxidative metabolism, cell division, death and photosynthesis. However, the mechanism of UWL production is poorly understood. In this study, hydrogen peroxide (H2O2) and tea polyphenols (TPs) were used to examine the relationship between delayed ultralight (UW-DL) and mitochondrial function and energy production during strawberry aging. The results showed that H2O2 treatment increased the O-2(center dot-) production and the malondialdehyde (MDA) content, decreased the H+-ATPase and Ca2+-ATPase activities, ATP content, energy load, and UW-DL intensity, while TP treatment retarded these effects. These results indicate that the accumulation of ROS accelerated the mitochondrial function impairment and decreased the ATP content. The intensity of UW-DL correlates positively with the concentration of in vitro mitochondria. H2O2 treatment decreased the UW-DL intensity in isolated mitochondria, suggesting that mitochondria are related to the production of UW-DL and that the accumulation of active oxygen reduces the capacity of mitochondria to produce UW-DL. Our results indicate that mitochondria are the main source of UW-DL in strawberry, cellular ATP plays an important role in the formation of UW-DL, and ROS may indirectly affect UW-DL by changing the structure and function of mitochondria.