| Summary: | Carbon is one of the most important nutrients for the development and secondary metabolism in fungi. CreA is the major transcriptional factor mediating carbon catabolite repression, which is employed in the utilization of carbon sources. <i>Aspergillus ochraceus</i> contaminates various food and feed containing different carbon sources by producing ochratoxin A (OTA). However, little is known about the function of <i>AoCreA</i> in regulating the morphology and OTA production of <i>A. ochraceus</i>. To give an insight into the mechanism of the carbon sources regulating development of <i>A. ochraceus</i> and OTA production, we have identified <i>AoCreA</i> in <i>A. ochraceus</i>. The homologous recombination strategy was used to generate the <i>AoCreA</i> deletion mutant (Δ<i>AoCreA</i>). We have investigated the morphology and OTA production of the wild type (WT) and Δ<i>AoCreA</i> of <i>A. ochraceus</i> with media containing different carbon sources (glucose, fructose, maltose, D-xylose, D-mannose, acetate, D-galactose, D-mannitol and lactose). Δ<i>AoCreA</i> showed a significant growth and conidiation defect on all media as compared with WT. Glucose and maltose were the most inducing media for OTA production by <i>A. ochraceus</i>, followed by sucrose and the nutrient-rich Yeast Extract Sucrose (YES) and Potato Dextrose Agar (PDA). The deletion of <i>AoCreA</i> led to a drastic reduction of OTA production on all kinds of media except PDA, which was supported by the expression profile of OTA biosynthetic genes. Furthermore, infection studies of Δ<i>AoCreA</i> on oats and pears showed the involvement of <i>AoCreA</i> in the pathogenicity of <i>A. ochraceus</i>. Thus, these results suggest that <i>AoCreA</i> regulates morphological development and OTA biosynthesis in response to carbon sources in <i>A. ochraceus</i>.
|
|---|