Figure 2.

Epistasis analysis suggests that Idr1 and Idr2 work together in the same genetic pathway. The growth rate of each strain is shown on the y-axis and metal conditions on the x-axis. Note that ‘0 iron’ refers to the fact that no iron was added to the medium. Iron levels in these media formulations were below the detection limits of ICP-MS (≤0.8 µM). Error bars represent ± SEM from the mean of at least six biological replicates and at most 20 (‘Materials and Methods’ section). Asterisks represent P < 0.05 in t-tests comparing the growth rate of the parent strain to those of each mutant. Symbols representing each mutant are described in the legend. Complete data sets for all growth experiments are listed in Supplementary Table S1 and representative growth curve plots are shown in Supplementary Figure S2.