Genome Wide Analysis Reveals the Role of VadA in Stress Response, Germination, and Sterigmatocystin Production in <i>Aspergillus nidulans</i> Conidia

• Main Authors: Ye-Eun Son, Hee-Soo Park
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Microorganisms
• Subjects: VadA; conidia; RNA-seq; ultraviolet stress; sterigmatocystin; germination
• Online Access: https://www.mdpi.com/2076-2607/8/9/1319

In the <i>Aspergillus</i> species, conidia are asexual spores that are infectious particles responsible for propagation. Conidia contain various mycotoxins that can have detrimental effects in humans. Previous study demonstrated that VadA is required for fungal development and spore viability in the model fungus <i>Aspergillus nidulans</i>. In the present study, <i>vadA</i> transcriptomic analysis revealed that VadA affects the mRNA expression of a variety of genes in <i>A. nidulans</i> conidia. The genes that were primarily affected in conidia were associated with trehalose biosynthesis, cell-wall integrity, stress response, and secondary metabolism. Genetic changes caused by deletion of <i>vadA</i> were related to phenotypes of the <i>vadA</i> deletion mutant conidia. The deletion of <i>vadA</i> resulted in increased conidial sensitivity against ultraviolet stress and induced germ tube formation in the presence and absence of glucose. In addition, most genes in the secondary metabolism gene clusters of sterigmatocystin, asperfuranone, monodictyphenone, and asperthecin were upregulated in the mutant conidia with <i>vadA</i> deletion. The deletion of <i>vadA</i> led to an increase in the amount of sterigmatocystin in the conidia, suggesting that VadA is essential for the repression of sterigmatocystin production in conidia. These results suggest that VadA coordinates conidia maturation, stress response, and secondary metabolism in <i>A. nidulans</i> conidia.