Figure 8.

Foliar treatment with flavonoids, and their effects on gall size and indole‐3‐acetic acid (IAA) level determined at 21 days post‐inoculation (dpi). (A) Phenotype of the shoots of Arabidopsis Col (DR5::GUS) plants treated with dimethylsulphoxide (DMSO) as control, the flavonoids kaempferol (K), naringenin (N) and quercetin (Q), and the auxin transport inhibitor N‐(1‐naphthyl)phthalamic acid (NPA). (B) Root phenotype of control and infected plants treated as in (A). Staining for β‐glucuronidase (GUS) activity reveals auxin responsiveness only in the parts of the roots in which gall development occurred. (C) Phytopathological analysis showing that the gall size was not reduced (for a detailed description of the parameters used, see text). (D) Free IAA levels in control and infected roots after treatment.