Figure 1. Iron depletion renders ΔsidN mutants incapable of axenic vegetative growth.

A. 16-day-old cultures of wild-type E. festucae Fl1 (WT) and ΔsidN mutant strains (ΔsidN 54 and ΔsidN 85) were grown on iron depleted defined media (DM), and DM media supplemented with 100 µM BPS, or 100 µM BPS and culture filtrate from WT (BPS CF), or 100 µM BPS and 20 µM FeS0₄ (BPS Fe²⁺) or 100 µM BPS and 20 µM FeCl₃ (BPS Fe³⁺) respectively. B. Radial growth measurements of WT, complement (C-sidN) and ΔsidN 85 were determined by inoculating mycelial plugs in triplicate onto DM media, or DM supplemented with 100 µM BPS, DM with 100 µM BPS and 20 µM FeS0₄ (Fe2+) and DM with 100 µM BPS and 20 µM FeCl₃ (Fe3+) respectively. Colonies were measured at 10 days. The results represent the mean of three independent experiments. The radial growth is normalized to that of WT grown on DM media.