Functional Evolution of Phosphatidylethanolamine Binding Proteins (PEBPs) in Soybean and Arabidopsis

Functional characterization of the conservation and divergence of duplicated genes that generated from different evolutionary stages will strengthen our understanding of how the fates of duplicated genes are determined. In this study, we systematically compared the functional variation of the phosphatidylethanolamine-binding proteins (PEBPs) in two species, Arabidopsisand soybean. Integrating phylogenetic analysis and genome duplication events enabled the deduction of an evolutionary process between the PEBP members. We then comprehensively investigated the functional variations in these PEBP members by performing a series of complementary tests, studying their interactions with AtFD, their subcellular localizations, and their expression patterns. The results demonstrated that nearly all the PEBP genes in soybean, both from ancient and recent duplications, exhibited divergence in expressional pattern, whereas functional divergence in protein level preferentially occurred between ancient duplications and only one gene may experience neo-functionalization, suggesting that sub-functionalization at expression and protein levels both play roles in stimulating the evolution of duplicated genes but may predominantly accumulate at different evolutionary stages. An associated analysis of the functional variation and sequence divergence of PEBP members reveal critical amino acid residues for the functional divergence of PEBP members, a subset of which was further validated by transgenic analysis.