Fig. 2

Nitrate- and stc promoter-dependent pyrG expression. a Schematic overview of A. niduans stc promoter driven pyrG test strains integrated at the yA locus. b A. nidulans strains were grown for 72 h at 37 °C on solidified GMM plates containing NH₄⁺ or NO₃⁻ as nitrogen and half of the plates were supplemented with 5 mM uracil/uridine as indicated. Green boxes indicate promoters with desirable traits of strict nitrate inducibility. c Schematic overview of spotting pattern of strains containing the indicated stc promoter driving pyrG on the plates depicted in panel (b). Bold letters indicate stc promoters with desired traits of nitrate inducibility. Cntr is the control strain TPMW7.2. d Northern blot analysis of all sterigmatocystin cluster genes from the A. nidulans WT and a ∆aflR knock-out mutant. Strains were grown in duplicate under sterigmatocystin production conditions (in 50 mL of GMM at 37° for 48 h at 250 rpm) before RNA extraction. Probes for indicated genes were hybridized and rRNA was visualized as loading control