Figure 5

A. brassicicola localization on A. thaliana seeds. Scanning electron microscopy a, b, c, e and f) and confocal laser scanning microscopy (d) images of Arabidopsis thaliana seeds (Ler ecotype) 10 days after inoculation with Alternaria brassicicola (Abra43). (a) Global colonization of a seed by A. brassicicola. (b) conidia formation on a seed. (c) direct hyphal penetration into the seed coat (white arrow). (d) mycelium development on a seed. Hyphae were stained with solophenyl flavin, and seed coat with propidium iodide. Hyphae grew on the seed surface, then penetrated into the seed coat (white arrows): hyphal brightness was lower when hyphae were growing within the seed coat. (e) and (f), alteration of the seed surface after fungal colonization: seed seemed shrivelled (e) by comparison with a seed harvested on a control plant (f).