Figure 3. Sexual development and virulence of F. graminearum strains.

(a) Sexual reproduction on carrot agar. Pictures were taken 7 days after sexual induction. Scale bar = 500 μm. (b) Virulence on wheat heads. A centre spikelet of each wheat head was injected with 10 μl of conidia suspension. Disease index (diseased spikelets per wheat head) is denoted below the picture. Asterisks indicate that the data differed significantly (P < 0.05) based on Tukey′s test. The pictures were taken 14 days after inoculation. Mock, negative control mock-inoculated with 0.01% Tween 20. (c) Sections of infected wheat heads. Wheat spikelets were inoculated with conidia suspensions of cytosolic Gfp-expressing F. graminearum strains. Infected wheat heads were dissected 6 days after inoculation and examined using fluorescence microscopy. Spreading of the Gfp signal represents spreading of hyphae from the points of inoculation. Arrows mark the inoculated spikelets. Reflected, reflected light.