Fig 8. Aspergilli RglT and KojR homologs are important for gliotoxin production and self-protection.

(A) Distribution of homologs of the gliotoxin and kojic acid biosynthetic gene clusters and of the RglT and KojR homologs amongst Aspergillus and Penicillium species. Homologs of the gliotoxin biosynthetic gene cluster are present across many (but not all) Aspergillus and Penicillium species, suggesting that the cluster was present in their common ancestor. Homologs of the kojic acid biosynthetic gene cluster are present only in Aspergillus oryzae and close relatives, suggesting that the cluster originated much more recently. Orthologs for RglT and KojR are broadly conserved in both genera, suggesting they were present in the Aspergillus–Penicillium common ancestor. Presence or absence of biosynthetic gene cluster homologs and of gene orthologs are depicted in black or white, respectively. (B-D) Pictures and graphs of the A. fumigatus (B), A. nidulans (C) and A. oryzae (D) wild-type, ΔrglT, and ΔkojR strains when grown for 48 h from 10⁴ conidia at 37°C on minimal medium (MM, A. fumigatus, A. nidulans) or PDA (A. oryzae) and MM/PDA+10 or 30 μg of gliotoxin. Graphs correspond to the radial diameter of the colony growth that is depicted in the pictures. Standard deviations represent the average of three biological replicates with *p < 0.05 in a one-tailed, paired t-test. (E) Detection of kojic acid (KA) production in A. oryzae in medium containing 1 mM ferric ion (FeCl₃). A red colour indicates the presence of KA chelated with ferric ions. The first and second rows indicate the top and bottom of the plates, respectively.