Figure 4.

Microscopic investigation of sexual developmental stages of the wild-type and double-knockout strains. Differential interference microscopy identified ascogonia (at 2 days), protoperithecia (at 3 days), pigmented protoperithecia (at 4 days), and perithecia (at 7 days) in the wild-type and mutant strains. Strains were grown on fructification medium and analyzed after growth at 25° for the number of days indicated. For examination of ascospore development, the content of perithecia was dissected. The perithecia of the Δppg1/Δppg2 mutant contained fewer asci and ascospores than the wild type. The sparsely produced perithecia of the Δpre1/Δppg1 and Δpre2/Δppg2 double mutants contain either ascus rosettes with viable ascospores or, in most cases, undifferentiated asci without ascospores. No perithecia, and thus no asci and ascospores, are produced in the Δpre1/Δpre2 mutant. Bars represent sizes in micrometers as indicated.