Carbon Catabolite Repression Gene AoCreA Regulates Morphological Development and Ochratoxin A Biosynthesis Responding to Carbon Sources in Aspergillus ochraceus

Abstract

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. Aspergillus ochraceus contaminates various food and feed containing different carbon sources by producing ochratoxin A (OTA). However, little is known about the function of AoCreA in regulating the morphology and OTA production of A. ochraceus. To give an insight into the mechanism of the carbon sources regulating development of A. ochraceus and OTA production, we have identified AoCreA in A. ochraceus. The homologous recombination strategy was used to generate the AoCreA deletion mutant (ΔAoCreA). We have investigated the morphology and OTA production of the wild type (WT) and ΔAoCreA of A. ochraceus with media containing different carbon sources (glucose, fructose, maltose, D-xylose, D-mannose, acetate, D-galactose, D-mannitol and lactose). ΔAoCreA 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 A. ochraceus, followed by sucrose and the nutrient-rich Yeast Extract Sucrose (YES) and Potato Dextrose Agar (PDA). The deletion of AoCreA 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 ΔAoCreA on oats and pears showed the involvement of AoCreA in the pathogenicity of A. ochraceus. Thus, these results suggest that AoCreA regulates morphological development and OTA biosynthesis in response to carbon sources in A. ochraceus.

AwAreA Regulates Morphological Development, Ochratoxin A Production, and Fungal Pathogenicity of Food Spoilage Fungus Aspergillus westerdijkiae Revealed by an Efficient Gene Targeting System

“…We speculated the hygR cassettes inserted randomly into chromosomes in other transformants mediated by NHEJ pathway. The efficiency of homologous replacement was 4.3%, similar to the efficiency of 7.8% for the knockout of AocreA ( Wang et al, 2020 ). For the parental strain Δ Awku70 , a total of 23 generated Δ AwAreA were obtained, with the homologous replacement efficiency of 95.7% ( Figure 3B ).…”

SakA Regulates Morphological Development, Ochratoxin A Biosynthesis and Pathogenicity of Aspergillus westerdijkiae and the Response to Different Environmental Stresses

“…One of the previous studies showed that A. ochraceus conidiospores on oats infected by the WT increased over time, whereas in oats that were infected by ∆AoCreA, the conidiospore numbers were significantly lower. On the other hand, pears infected with the WT showed a rapid increase in lesions, whereas the lesions in ∆AoCreA were small and they were not rapidly expanding [49].…”

“…Reagents were obtained from the supplier of Solarbio (Beijing, China) except for special markings. The infestation experiments of agricultural products were performed according to the conventional treatment method [49].…”

Genomic footprints related with adaptation and fumonisins production in Fusarium proliferatum

“…Carbohydrate metabolic process (GO:0005975) was shown the association with fumonisins production in F. proliferatum ( Table 3 ). The sources of carbon available were reported to play a critical role in induction of SM biosynthesis, such as fumonisins biosynthesis in F. verticillioides ( Malapi-Wight et al, 2013 ), aflatoxin production in A. flavus ( Fasoyin et al, 2018 ), ochratoxin A biosynthesis in Aspergillus ochraceus ( Wang et al, 2020 ). Glucose is the preferred carbon source for the filamentous fungi.…”