Macroconidial defect in Δ<i>Fghtf1</i> mutant.

<p>(A) Budding pattern of macroconidial development in <i>F. graminearum.</i> Wild-type PH-1 strain produced incipient macroconidium without distinct septation directly from hyphae. <i>ΔFghtf1</i> deletion mutant produced matured conidium with clear septation from the tip of hyphae. The resulting cells were observed with a DIC microscope and also stained with DAPI and calcofluor white (CFW) to visualize nuclei and septa, respectively, under a fluorescence microscope. Black arrows in PH-1 strain indicated the position of cell division. s, septa, n, nucleus. Bar = 20 µm. (B) Macroconidia matured and then released from the hyphae by mechanical force during incubation with agitation. <i>ΔFghtf1</i> mutant was stained with calcofluor white (CFW) to visualize cell wall and septa. White arrows indicate the point of breakage. Bar = 20 µm. (C) Morphological phenotypes of macroconidia produced by PH-1 and <i>ΔFghtf1</i> mutant. a, PH-1, typical <i>Fusarium</i> macroconidium, the apical cell is in the below (black arrow), and the foot cell is on the top (white arrows). b–d, <i>ΔFghtf1</i> mutant, an obvious defect in foot cell. Bar = 20 µm.