Figure 2.

The ∆gcnE mutant is impaired in conidiation. (A) Wild type (WT) and ∆gcnE strains were grown vegetatively for 18 hr, and then conidiation was induced in complete medium. Progression of the developmental program was followed under the stereo microscope at the indicated time points. Conidiophore heads were evident after 10 hr of induction in the wild-type strain. Yellow conidia were evident 24 hr after induction. No such structures were seen in the ∆gcnE strain even after 72 hr of induction. (B) Comparision of the conidiation phenotype of wild-type and ∆gcnE strain with the phenotypes of the mutants in the central regulatory pathway (∆brlA, ∆abaA, or ∆wetA) after 4 days of growth. The brlA mutant produced the stalk cells and then continued growing rather than developing the conidiophore vesicles, metulae, phialides, and conidia. Mutations in abaA and wetA interfered in later stages of conidiophore development and were capable of producing white structures corresponding to the vesicles, metulae, and phialides. The ∆gcnE strain resembles a ∆brlA phenotype. (C) SEM images of the wild-type and ∆gcnE strains grown for 1 week. A very low density of immature conidiophores can be observed in the ∆gcnE strain, compared to the complete development of the wild-type conidiophores. Bar, 50 µm. (D) Details of SEM images comparing the wild-type conidiophores with the aberrant ∆gcnE conidiophore morphologies (indicated by arrows). Arrows indicate details of aberrant conidiophores. The double-line arrow points to a severe example where sterigmata cells seem to bud off from a hyphal or stalk cell. A higher magnification of this example is shown as a separate image at the top right. Bar, 10 µm, except for the top right image where the bar corresponds to 5 µm.