Cold plasma reduces the incidence of Botrytis cinerea infection in grape fruit by affecting the energy status and respiratory metabolism

Table grapes possess thin skins and a high moisture content, making them particularly susceptible to mechanical damage and fungal infection during shipping and storage, leading to deterioration. Cold plasma (CP) technology is an innovative nonthermal sterilization method that effectively inhibits microbial growth. This study investigated the effects of CP treatment on disease development, respiratory metabolism, and energy status of grapes inoculated with Botrytis cinerea. CP treatment significantly reduced the disease index, lesion diameter, and respiration rate of inoculated grapes. It inhibited the disease-induced decrease in energy charge level, reduced the activities of phosphohexose isomerase (PGI), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), inhibited the decrease in glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). Treatment with CP increased nicotinamide adenine dinucleotide (NAD) kinase activity, decreased NAD and NADH levels, increased NADP and NADPH levels. It inhibited the reduction in ATPase activity of the inoculated fruit and delayed the decrease in adenosine triphosphate (ATP) and adenosine diphosphate (ADP) contents, while reducing the adenosine monophosphate (AMP) content. In summary, CP treatment could inhibit respiratory metabolism and maintain a higher energy status by suppressing the rise in grape respiratory metabolizing enzyme activity, inhibiting the glycolysis-tricarboxylic acid cycle and cytochrome pathway, and augmenting the pentose phosphate pathway to suppress respiratory metabolism, thereby effectively reducing disease development in grapes.