Plant Biology 2008 location:Merida, Mexico date:26 June-1 July
The non-reducing disaccharide trehalose and its intermediate trehalose 6-phosphate (T6P) are emerging as two molecules with an increasing unexpected importance in plant cell biology and beyond. Recently it has been shown that trehalose (α-D glucopyranosyl 1, 1-α-D glucopyranoside) metabolism plays an important role in plant development, carbohydrate metabolism, glucose sensing and ABA metabolism suggesting a hormone function for T6P. The most common trehalose biosynthetic pathway involves two enzymatic reactions carried out by the enzymes trehalose 6-phosphate synthase and trehalose 6-phosphate phosphatase, present in both prokaryotic and eukaryotic organisms. The unknown origin and presence of the eukaryotic TPS multigene families in plants makes it a big challenge to understand the role of trehalose metabolism. Here we show the origin and evolutionary history of the plant trehalose biosynthesis pathways. We characterized a novel TPS-TPP bifunctional protein (TPSP) from the bacteria Cytophaga hutchinsonii and the whole TPS family of the algae Ostreococcus tauri, as well as the trehalose phosphate phosphatase of the bacteria Rhodopherax ferrireducens likely members of the plant class I, II and III ancestor groups. Our results shows that ChTPSP is a bifunctional protein resulted from a fusion of bacterial TPS and TPP genes before the eukaryotic divergence. In the Eukaryote lineage these fused proteins were duplicated almost immediately to generate the plant class I and II proteins. Class III proteins were recruited by plants from a different ancestor. Gene duplication and recruitment of new regulatory elements present in higher plants were initiated very early in plant evolution.