FfG1 has distinct functions as a repressor for fusarubin biosynthesis.

<p>The WT, Δ<i>ffG1</i> and <i>ffG1</i>^G42R mutants were grown in ICI synthetic media either under fusarubin biosynthesis-repressing (6 mM glutamine (Gln)) or fusarubin biosynthesis-favoring (sodium nitrate (NO₃⁻)) conditions. A) After 7 days of incubation, culture filtrates were used for HPLC-DAD analysis (for details see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058185#s2" target="_blank">material and methods</a>). Photographs show the flask with the culture broth after 7 days of growth and the corresponding HPLC chromatogram at 450 nm. Brackets indicate metabolites found in the liquid culture: bikaverins (BIK) and fusarubins (FSR). The scale for <i>ffG1</i>^G42R was set to 20 mAU due to a lower accumulation of compounds in the liquid culture compared to the other strains. B) After 3 and 4 days, mycelia were harvested and used for northern blot analysis. The genes <i>fsr1</i> and <i>fsr2</i> (as examples for fusarubin biosynthetic genes) and <i>bik2</i> (as an example for bikaverin biosynthetic genes) were used as probes. C) WT and Δ<i>ffg1</i> were grown under fusarubin biosynthesis-favoring conditions. After 4 days of growth either glutamine, sodium nitrate or no nitrogen was added and after another 30 min mycelia were harvested and used for Northern blot analysis, <i>fsr2</i> was used for probing.