BcLTF1 is needed to cope with oxidative stress and regulates the generation of ROS.

(A) Radial growth rates of Δbcltf1 mutants are affected by supplements. Strains were incubated in LL (white), LD (gray), or DD (black) on solid CM (control), and CM with 0.7 M NaCl, 0.7 M sorbitol, 300 µM menadione, 7.5 mM H2O2, 800 µM DTT (dithiothreitol) or 28 mM AA (ascorbic acid). Mean values and standard deviations were calculated from five colonies per strain and condition. Asterisks indicate significant differences compared to WT:B05.10 in each condition (p<0.001). (B) Salt and oxidative stress prevent growth of Δbcltf1 mutants even in the absence of light. Pictures were taken after 2 d in DD. (C) Ascorbic acid and DTT restore light tolerance but not the proliferation of aerial hyphae. Pictures were taken after 2 d in LL. Hardly visible Δbcltf1 colonies are highlighted by dashed lines. (D) Bcltf1 mutants are affected in generation of H2O2. Strains were incubated for 2 d in DD on CM or CM supplemented with 750 µM DTT. Then, colonies were flooded with DAB solution. DTT prevents oxidation of DAB in the range of wild-type colonies but not in the range of Δbcltf1 colonies (on the left). Identical quantities of fresh mycelia of B05.10, Δbcltf1 (A6, B1) and OE::bcltf1 (T6, T7) were incubated in DAB solution (on the right). (E) The cytosolic glutathione redox potential is not significantly affected in the absence of bcltf1. Reactions of redox-sensitive reporter roGFP2 expressed in Δbcltf1 and wild type were compared. Reduction of roGFP2 is displayed after an oxidation event provoked by addition of 10 mM H2O2 after 2 min. Indicated values are the means of triplicates; standard deviations are shown. For details, see Materials and Methods.