The plant pathogenic fungus Penicillium expansum is a major concern of the global food industry due to its wide occurrence and ability to produce various mycotoxins, of which the most significant is patulin. Although the patulin gene cluster has been recently identified and characterized, little is known on how it is regulated. Here we demonstrate that LaeA, a global regulator of mycotoxins in other fungi, is also required for the production of not only patulin but also other putative toxic secondary metabolites (SMs) produced by P. expansum as well as virulence on apple. We find that an increase of the sucrose molarity in the culture medium from 15 to 175 mM positively impacts creA expression, but conversely, decreases the expression of laeA and the accumulation of patulin by 5 and 175 fold, respectively. The increase in sucrose also negatively influences the expression of most of the SM synthase genes in P. expansum Pe-D1 strain. Independently, LaeA was deemed as a positive regulator of at least 6 SM gene clusters. Here we address the hypothesis that CreA regulation of laeA mediates many of the ΔlaeA phenotypes including regulation of SM clusters and virulence on apple.
Full conference title:
- Asperfest 14 (2017)