Environmental and genetic components of flavonoid variation in red oak, Quercus rubra

Abstract

Two elevation-related chemotypes of red oak ( Quercus rubra L.) occur in the southern Appalachians. Studies were carried out to evaluate the effects of genetic and environmental factors on these flavonoid profiles. Low elevation trees which contain only kaempferol and quercetin glycosides were used for assessment of within-tree variation. Within a single tree, sun, shade and branch position have only minor quantitative effects on the flavonoid array. To assess the effect of growing locality on flavonoid profiles we collected red oak acorns from eight locations spanning 1455 m elevation in NC and VA, and divided them equally between nursery plots at 75 and 1140 m in elevation. After five years, leaves of each tree were collected and analysed for flavonoid content and quantity. Myricetin-rich high elevation and quercetin-rich low elevation individuals retain their distinctive profiles regardless of planting size. Some quantitative intrapopulational variation in flavonoid constituents exists between high and low elevation grown trees, but is slight and primarily restricted to minor components. Populations from middle elevations are more heterogeneous than those from either high or low elevations. Some of these trees have lower quantities of myricetin glycosides than high elevation trees while others lack them entirely.