Fig. 1

Plasmodia, resting spores, and germination of resting spores (zoospores) of P. brassicae. a Multinucleate plasmodia in a root cortical cell of B. napus; the left upper corner shows an enlarged portion from the white square frame showed membranes of two plasmodia (white arrows); N, nucleus. b Mature resting spores in cortical cells of roots of B. napus. c Resting spores observed by transmission electron microscopy. d Germinated resting spores (large) and zoospores (small) stained with 4′,6-diamidino-2-phenylindole. The resting spores are empty, with no nuclei present