Horizontal gene transfer of alpha-amylase genes from A. oryzae to A. niger CBS 513.88. (A) Unmatched region identified for the left arm of chromosome III spanning 65 kb for ATCC 1015 encoding 30 predicted genes and 85 kb for CBS 513.88 encoding 24 predicted genes. The unmatched region is flanked on one side by a small local inversion of three predicted genes (in green). (B) The 12.4-kb HGT region is part of an identical 12.7-kb region present in A. oryzae RIB40 supercontigs SC113 and SC023. In A. niger CBS 513.88, the transferred region is enclosed by a 203-bp inverted repeat (red arrow). An12g07000 (blue) is a putative transposase and identical to the A. oryzae transposon Aot1 tnpA gene. Similarly, the A. niger CBS 513.88 alpha-amylase encoding gene An12g06930 (orange) is identical to A. oryzae annotated genes AO090120000196 (SC113) and AO090023000944 (SC023). (C) Proposed duplication–recombination event between supercontig 12 and supercontig 05 of the 12-kb HGT region. Breakpoints are indicated with dotted lines. The fragment encoding alpha-amylase An05g02200 is identical to An12g06930 (orange). The breakpoints are flanked with additional copies of the 203-bp repeat region (red arrow). The region encoding genes An12g06940 to An12g06970 is identical to the region encoding An05g02210 to An05g02130. The downstream breakpoint occurred in the predicted gene coding region of An12g06970, thereby deleting the original start codon and upstream region.
