Chemotactic response of A. euteiches zoospores to various substances over a period of 4 h. A, Experiments with standards. Gum arabic was used at 0.1% (w/v), citrus pectin at 1% (w/v), and β-GlcY at 5 µm. B, Experiments with plant-derived material. The root exudate represents material collected from four roots. Bars plot means ± se of three replicates, based on 200 zoospores per replicate. AGP, Arabinogalactan proteins.