Potential impact of soil microbiomes on the leaf metabolome and on herbivore feeding behavior

Summary It is known that environmental factors can affect the biosynthesis of leaf metabolites. Similarly, specific pairwise plant–microbe interactions modulate the plant's metabolome by stimulating production of phytoalexins and other defense-related compounds. However, there is no information about how different soil microbiomes could affect the plant growth and the leaf metabolome. We analyzed experimentally how diverse soil microbiomes applied to the roots of Arabidopsis thaliana were able to modulate plant growth and the leaf metabolome, as assessed by GC-MS analyses. Further, we determined the effects of soil microbiome-driven changes in leaf metabolomics on the feeding behavior of Trichopulsia ni larvae. Soil microbiomes differentially impacted plant growth patterns as well as leaf metabolome composition. Similarly, most microbiome-treated plants showed inhibition to larvae feeding, compared with unamended control plants. Pyrosequencing analysis was conducted to determine the soil microbial composition and diversity of the soils used in this study. Correlation analyses were performed to determine relationships between various factors (soil microbial taxa, leaf chemical components, plant growth patterns and insect feeding behavior) and revealed that leaf amino acid content was positively correlated with both microbiome composition and insect feeding behavior.