Ageing-dependent responses of phloem flavonoids of Prunus avium graftings: Flavanone-, flavone- and isoflavone-glucosides

The qualitative and quantitative patterns of several flavonoid glucosides in the phloem of shoots and stems of Prunus avium during ageing were determined. The flavonoids investigated were the flavanones dihydrowogonin 7-glucoside, prunin and sakuranin, the isoflavone genistin and the flavone chrysin 7-glucoside. All flavonoids increased in senescing interspecific graftings as compared to healthy homospecific ones. Increasing levels of prunin and sakuranin were related to advancing age of the branch sections within the crown. Comparing the 1-year-old phloem from 2- and 8-year-old trees, chrysin 7-glucoside increased about three times in the older crowns. During seasonal shoot ontogeny from February to October, chrysin 7-glucoside levels increased and the values in October for genistin were about 9 times those in April, and they then declined during the dormant season. The seasonal increase of prunin and sakuranin was comparatively slight. Conversely, dihydrowogonin 7-glucoside declined from April to October. Some other flavonoids did not change in relation to shoot or tree ontogeny.