Figure 2.

Structures of the mt-nad9 and ct-ndhC genes of ten green plants, showing interorganellar transfer of segment no. 22 DNA from the ct to mt genome in a common ancestor of the cereal and the origin of the wheat mt-nad9 gene by expansion of its coding region to include the 5′-flanking region where segment no. 22 was transferred. Numbers given in the figure: nucleotide position of the respective borders. Double-lined arrow: transfer of segment no. 22 in the ct-ndhC to the 5′-flanking region of mt-nad9 in a common ancestor of the cereal. Nucleotide 1 of each gene is the third nucleotide of its stop codon.