Figure 4.

Possible mechanism of gene and genome size expansion of A. oryzae. (A) The common ancestor of the three Aspergillus species (A. oryzae, A. fumigatus and A. nidulans) is assumed to have smaller genome size of A. oryzae and similar size to A. fumigatus and A. nidulans. Aspergillus oryzae might have acquired genetic materials (represented by hatched boxes) during evolution. (B) The common ancestor is assumed to have the genome size similar to A. oryzae. The other two species might have lost genetic materials (represented by open boxes) during evolution. The phylogenetic relationship of the three species⁴² is indicated. (C) The A. oryzae genome size might have been expanded by the gene duplication followed by divergence of one of the duplicated genes (represented by hatched boxes).