Figure 3.

Variation in acylsucrose acyltransferases in a phylogenetic context. A combination of enzymology, metabolite profiling, genomics and transcriptomics approaches led to a model for evolution of the core acylsucrose biosynthetic network over the tens of millions of years since divergence from the last common ancestor with Convolvulaceae [8]. The rectangular boxes represent ASAT homologs found in the corresponding species. The same color represents the closest ASAT homologs across species. All ASATs shown were biochemically characterized except the ones in Solanum nigrum and Hyoscyamus niger. The triacylated sucroses with all acyl chains on the pyranose ring (P-type acylsucroses) produced by S. pennellii have the same acylation pattern as those produced in Petunia and Salpiglossis. However, the enzymes, and the order of acylation to produce these P-type acylsucroses, differ as depicted. In fact, ‘flipped pathway’ leading to synthesis of the S. pennellii P-type acylsucroses appears to be a metabolic innovation that originated after the last common ancestor of the Solanum tomato clade and before the divergence from the last common ancestor of S. pennellii and S. habrochaites. This model is consistent with P-type acylsucroses evolving multiple times in the Solanaceae.