FIG. 3.

Lack of CG in the ΔPaTrx1 ΔPaTrx3 and ΔPaTrx1 ΔPaTrx2 ΔPaTrx3 strains. On the left is depicted the experimental setup. A culture is grown for 7 days on M2 medium supplemented with methionine, and explants taken at various distances from the growing edge are replicated onto M2 medium supplemented with yeast extract. The C element responsible for CG is induced in the stationary phase and triggers CG in explants taken from the part of the thallus that is in the stationary phase. In contrast, explants taken from the growing edge yield mycelia in normal growth (NG) conditions. CG is visible in wild type grown on M2 plus yeast extract as a flat and spindly growth with pigment accumulation (8, 37). In the ΔPaTrx1 ΔPaTrx3 mutant, growth impairment is much reduced and visible as a slightly flatter mycelium. In the ΔPaTrx1 ΔPaTrx2 ΔPaTrx3 mutant no discernible CG was observed. Note that the mycelium from this strain grows more slowly, produces fewer aerial hyphae, and accumulates more pigment on M2 supplemented with yeast extract than normal-growing wild-type strains.