Datensatz

Zusammenfassung

A few studies in the past have shown that plant diversity in terms of species richness and
functional composition can modify plant defense chemistry. However, it is not yet clear to
what extent genetic differentiation of plant chemotypes or phenotypic plasticity in response
to diversity-induced variation in growth conditions or a combination of both is responsible
for this pattern. We collected seed families of ribwort plantain (Plantago lanceolata) from
six-year old experimental grasslands of varying plant diversity (Jena Experiment). The offspring
of these seed families was grown under standardized conditions with two levels of
light and nutrients. The iridoid glycosides, catalpol and aucubin, and verbascoside, a caffeoyl
phenylethanoid glycoside, were measured in roots and shoots. Although offspring of
different seed families differed in the tissue concentrations of defensive metabolites, plant
diversity in the mothers' environment did not explain the variation in the measured defensive
metabolites of P. lanceolata offspring. However secondary metabolite levels in roots and
shoots were strongly affected by light and nutrient availability. Highest concentrations of iridoid
glycosides and verbascoside were found under high light conditions, and nutrient availability
had positive effects on iridoid glycoside concentrations in plants grown under high
light conditions. However, verbascoside concentrations decreased under high levels of
nutrients irrespective of light. The data from our greenhouse study show that phenotypic
plasticity in response to environmental variation rather than genetic differentiation in
response to plant community diversity is responsible for variation in secondary metabolite
concentrations of P. lanceolata in the six-year old communities of the grassland biodiversity
experiment. Due to its large phenotypic plasticity P. lanceolata has the potential for a fast
and efficient adjustment to varying environmental conditions in plant communities of different
species richness and functional composition.