Fig. 8

The multinucleate architecture of B. lactucae. Lettuce cotyledons infected with B. lactucae stained with 4’,6-diamidino-2-phenylindole (DAPI) to render nuclear DNA fluorescent. a Densely multinucleate coenocytic mycelium growing between spongy mesophyll cells of a non-transgenic lettuce cotyledon five days post infection (dpi), prior to sporulation. Two of several multinucleate haustoria that have invaginated the host plasmalemma are indicated (h). The larger plant nuclei fluoresce purple. Auto-fluorescent chloroplasts are visualized as green. b Infected lettuce cotyledon stably expressing DsRED stained seven dpi at the onset of sporulation. The multinucleate stem of a sporangiophore is visible exiting a stoma. Two multinucleate spores are visible on the cotyledon surface (arrowed). Small DAPI-stained bacterial cells are also visible. Scale bars in each represent 15 μm