When gene marriages don't work out: divorce by subfunctionalization

We describe how a bifunctional gene, encoding two proteins by alternative splicing, arose when the chloroplast gene RPL32 integrated into an intron of the nuclear gene SODcp in an ancestor of mangrove and poplar trees. Mangrove retains the alternatively spliced chimeric gene, but in poplar it underwent duplication and complete subfunctionalization, through complementary structural degeneration, to re-form separate RPL32 and SODcp genes.