Effects of phloridzin, phloretin and benzoic acid at the concentrations measured in soil on the root proteome of Malus hupehensis Rehd Seedlings

In this study, the effects of phloridzin, phloretin and benzoic acid on the root proteome of Malus hupehensis Rehd seedlings under the sandy culture conditions were investigated. The applied concentrations of phloridzin, phloretin and benzoic acid were the measured concentrations in soil. Compared with the control group, a total of 16 differentially expressed protein spots (10 up-regulated and 6 down-regulated), 13 differentially expressed protein spots (4 up-regulated and 9 down-regulated) and 9 differentially expressed protein spots (3 up-regulated and 6 down-regulated) were detected in the root systems after the M. hupehensis Rehd seedlings were treated with phloridzin, phloretin or benzoic acid, respectively. The identified protein spots could be classified into 8 functional groups as follows: signal transduction-related proteins, pathogenesis-related proteins, metabolism related proteins, free radical scavenging proteins, stress resistance-related proteins, cytoskeleton-related proteins, allergen-related proteins and proteins with unknown functions. Under the stresses of phloridzin, phloretin and benzoic acid treatments, the expression levels of defense system-related proteins and free radical scavenging proteins in their root system were up-regulated, indicating that the phenolic compounds, such as phloridzin, phloretin and benzoic acid, could cause damaging effects on M. hupehensis Rehd seedlings, leading to the up regulation of defense system-related proteins. This study further revealed that the action mechanisms by which phenolic compounds play their roles in apple replant disease (ARD), which could provide useful information for comprehensive control and prevention of ARD.