Changes in phenol content during strawberry (Fragaria x ananassa, cv. Chandler) callus culture

Total soluble phenols, soluble flavanols, (+)-catechin, ferulic acid and 1-O-feruloyl-beta -D-glucose were analyzed during the development of a strawberry (Fragaria x ananassa, ev. Chandler) callus culture. The time-course changes of the different phenols assayed were well correlated with callus growth and morphology. The changes in polyphenol oxidase (EC 1.10.3.12) and beta -glucosidase (EC 3.2.1.21) activities in the callus were also examined. The total phenol, soluble flavanols and (+)catechin contents were high during the preexponential and exponential phases of growth. The subsequent decrease in ( +)-catechin concentration coincided with high levels of polyphenol oxidase activity. The 1-O-feruloyl-beta -D-glucose content was highest as callus growth ceased, and its subsequent decrease was accompanied by the increased production of ferulic acid. This increase in ferulic acid was accompanied by an increase in beta -glucosidase activity. The ferulic acid content decreased at the end of culture, when callus growth had stopped and showed clear symptoms of senescence. This decrease in the ferulic acid concentration was accompanied by an increase in the levels of ferulic acid bound to cell wall components.