Elevated CO2 exposure induces core browning in Yali pears by inhibiting the electron transport chain.

• High CO 2 concentrations caused core browning. • Core browning and damage of cellular membrane increased in 4% CO 2 condition. • H 2 O 2 and malondialdehyde increased in 4% CO 2 condition. • CO 2 regulate electron transport chain and reactive oxygen species scavenging enzymes. Pears may be affected by core browning during storage, reducing their commercial value. The effect of CO 2 stress on the core browning process in Yali pears was investigated. Exposure to a 4% CO 2 atmosphere significantly increased the core browning and reduced titratable acidity and soluble solids content. The activity of succinate dehydrogenase and peroxidase was reduced in CO 2 -stressed pears, whereas the levels of H 2 O 2 and malondialdehyde were increased. Transmission electron microscopy revealed significant damage to cellular membrane structure in the core tissues of CO 2 -stressed pears. In addition, CO 2 -stressed pears showed increased polyphenol oxidase activity. These results suggest that high concentrations of carbon dioxide can accelerate core browning in pears by inhibiting the activities of enzymes in the electron transport chain, resulting in increased levels of free radicals that damage cellular membranes. [ABSTRACT FROM AUTHOR]