Iron regulator crucial for the adaptation to iron starvation and iron excess, but is dispensable for virulence (PubMed:26960149). SreA represses the expression of hapX and the siderophore system during iron sufficient conditions by an iron-sensing mechanism, while hapX represses sreA and activates the siderophore system during iron-limiting conditions, resulting in efficient iron uptake and inhibition of iron-consuming pathways (PubMed:26960149). HapX targets include genes encoding a number of key iron-regulated factors such as the vacuolar iron importer cccA, as well as hemA, cycA and lysF involved in heme biosynthesis, respiration and lysine biosynthesis, respectively (PubMed:26960149). Activation of the vacuolar iron importer cccA during high iron conditions is essential for iron detoxification (PubMed:26960149). Expression is highly up-regulated during iron starvation (PubMed:26960149). Leads to reduced growth and decreased conidiation during iron starvation, but not during iron-replete conditions (PubMed:26960149). Showed a reddish pigmentation of mycelia during iron-depleted conditions probably due to the accumulation of iron-free precursors of heme (PubMed:26960149). Results in a lacking activation of the siderophore biosynthesis genes sidA and sidC during iron starvation and in a decreased production of extracellular ferrichrome C, but not ferricrocin (PubMed:26960149). Results also in complete deregulation of genes from iron-dependent pathways such as vacuolar iron storage, amino acid metabolism, respiration and heme biosynthesis during iron limitation (PubMed:26960149). Belongs to the bZIP family. YAP subfamily.