Abstract
Plant and soil biodiversity can
have significant effects on herbivore resistance mediated by plant
metabolites. Here, we disentangled the independent effects of plant
diversity and soil legacy on constitutive and herbivore-induced plant
metabolomes of three plant species in two complementary microcosm
experiments.
First, we grew plants in sterile soil with three different plant
diversity levels. Second, single plant species were grown on soil with
different plant diversity-induced soil legacies. We infested a subset of
all plants with Spodoptera exigua larvae, a generalist
leaf-chewing herbivore, and assessed foliar and root metabolomes.
Neither plant diversity nor soil legacy had significant effects on
overall foliar, root, or herbivore-induced metabolome composition.
Herbivore-induced metabolomes, however, differed from those of control
plants. We also detected 139 significantly regulated metabolites by
comparing plants grown in monocultures with conspecifics growing in
plant or soil legacy mixtures. Moreover, plant-plant and plant-soil
interactions regulated 141 metabolites in herbivore-induced plants.
Taken together, plant diversity
and soil legacy independently alter the concentration and induction of
plant metabolites, thus affecting the plant’s defensive capability. This
is a first step towards disentangling plant and soil biodiversity
effects on herbivore resistance, thereby improving our understanding of
the mechanisms that govern ecosystem functioning.
Keywords: Aboveground-belowground interactions,
Biodiversity-ecosystem function, Chemical diversity, Eco-metabolomics,
Herbivory, Metabolite profile