Effects of β-cedrene and α-humulene on Arabidopsis thaliana root growth. a Number of root branches produced by seedlings exposed to different concentrations of the sesquiterpenes (SQTs) β-cedrene or α-humulene; b effects of adding β-cedrene (10 ppb) or α-humulene (10 ppb) to culture medium containing lovastatin (Lov) (which inhibits the synthesis of Suillus bovinus (Sb) SQTs) on root branching, n = 15. Data shown are means ± the SE. Different letters above bars indicate significant differences between treatments (P < 0.05).