Figure 3.

Essential roles of Frq1 and Frq2 in non-rhythmic conidiation of B. bassiana. (A) Conidial yields (symbols) measured from the SDAY cultures of frq mutants and WT during a 10-day incubation at 25 °C in five different L:D cycles and those fitted to daylight length (l_d) and incubation time (t). The fitted curves and equations indicate a significant dependence of conidial yield (y in a scale of 10⁷ conidia cm⁻²) on l_d and t (P < 0.0001) and a great difference in conidiation capacity between Δfrq mutants and control strains. (B) Scanning electronic microscopic (SEM) images (scale = 5 μm) for conidiation status of indicated strains in the 7-day-old cultures grown at 25 °C and L:D 12:12. Note that early conidiating structures were present in Δfrq1 (arrowed) but absent in Δfrq2. (C) Biomass levels measured from the 7-day-old SDAY cultures grown at 25 °C in five photoperiods. (D) Relative transcript levels of related genes in the 3-day-old SDAY cultures of frq mutants versus WT grown at 25 °C under light (L:D 24:) and in darkness (L:D 0:24). The dashed line denotes a significance for one-fold repression or up-regulation. All SDAY cultures were initiated by spreading 100 μL of a 10⁷ conidia mL⁻¹ suspension per plate (9 cm diameter). Error bar: SD of the mean from three replicates (A,C) or cDNA samples (D) analyzed through qPCR with paired primers (Table S2).