Effects of the auxin synthesis inhibitor yucasin and the auxin transport inhibitor 1‐N‐naphthylphthalamic acid (NPA) on Arabidopsis thaliana lateral root branch development induced by Suillus bovinus volatile organic compounds (VOCs). a Effects of adding different concentrations of yucasin to medium inoculated with S. bovinus or containing β-cedrene or α-humulene; b effects of adding different concentrations of NPA to medium inoculated with S. bovinus or containing β-cedrene or α-humulene. n = 15. Different letters above bars indicate significant differences between treatments (P < 0.05).