Aspergillus oryzae atfA controls conidial germination and stress tolerance

We compared atfA and atfB, the genes encoding the respective ATF/CREB-type transcription factors in Aspergillus oryzae. The germination ratio of ΔatfA conidia was low without any stress, unlike that of ΔatfB conidia. The ΔatfA conidia were more sensitive to oxidative stress than the ΔatfB conidia, which are also sensitive to oxidative stress. We compared the gene expressions of these strains by using a DNA microarray, GeneChip. Almost all the genes regulated by atfB were also regulated by atfA, but atfA also regulated many genes that were not regulated by atfB, including some genes putatively involved in oxidative stress resistance. The level of glutamate, the major amino acid in A. oryzae conidia, was significantly low only in the ΔatfA conidia, and the glycerol accumulation during germination was not observed only in the ΔatfA strain. We therefore concluded that atfA is involved in germination via carbon and nitrogen source metabolism.