Fusarium head blight symptoms and penetration sites on Bd spikes. a) Typical early FHB symptoms on point inoculated wheat spike. b) Typical late FHB symptoms on point inoculated wheat spike displaying bleaching. c - e) FgUK1 spray inoculation symptoms: 3, 7 and 14 dpi, respectively. f & g) FgUK1 point inoculation, same spike 2 and 4 dpi, respectively. h) FgUK1 symptoms following spray inoculation with maintained high humidity. Scale bars a-h = 1 cm. i-p) Light microscope images of detached Bd21 florets, 3dpi with Fg, cleared and stained with aniline blue. i) External surface of lemma showing hyphal contact on macro-hairs (arrows). j & k) are close ups of picture i) taken at different focal planes. j) shows hyphal strands enveloping the macro-hair and k) shows a globose fungal structure formed at the base of the macro-hair (bmh). l) Internal surface of the palea showing hyphal colonization, necrosis and accumulation of phenolic compounds in corrugated circular cells (arrow). m & n) Macro-hair base of lemma at early stage of fungal colonization showing aggregated hyphal structure, n) Macro-hair base of lemma at late stage of fungal colonization showing extensive hyphal strands enveloping the base of the macro-hair, intense phenolic compound accumulation and collapse of the macro-hair. o-p) External surface of the palea showing the base of a macro-hair and neighbouring corrugated circular cell (arrow head) accumulating phenolic compounds (o) in response to hyphal contact (p), Upper arrow points at globose structure located above the corrugated circular cell and lower arrow pointing at hyphal strands in contact with the base of the macro-hair. Scale bars i-p = 20 μm.
Peraldi et al. BMC Plant Biology 2011 11:100 doi:10.1186/1471-2229-11-100