Positive selection driving diversification in plant secondary metabolism.
In Arabidopsis thaliana and related plants, glucosinolates are a major component in the blend of secondary metabolites and contribute to resistance against herbivorous insects. Methylthioalkylmalate synthases (MAM) encoded at the MAM gene cluster control an early step in the biosynthesis of glucosinolates and, therefore, are central to the diversification of glucosinolate metabolism. We sequenced bacterial artificial chromosomes containing the MAM cluster from several Arabidopsis relatives, conducted enzyme assays with heterologously expressed MAM genes, and analyzed MAM nucleotide variation patterns. Our results show that gene duplication, neofunctionalization, and positive selection provide the mechanism for biochemical adaptation in plant defense. These processes occur repeatedly in the history of the MAM gene family, indicating their fundamental importance for the evolution of plant metabolic diversity both within and among species.
Benderoth
Markus
M
Department of Genetics, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany.
Textor
Susanne
S
Windsor
Aaron J
AJ
Mitchell-Olds
Thomas
T
Gershenzon
Jonathan
J
Kroymann
Juergen
J
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D003062:Codon; D019143:Evolution, Molecular; D014644:Genetic Variation; D005961:Glucosinolates / Q000096:biosynthesis; D008969:Molecular Sequence Data; D005810:Multigene Family; D007652:Oxo-Acid-Lyases / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D012641:Selection, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D029681:Arabidopsis Proteins; D003062:Codon; D005961:Glucosinolates; D007652:Oxo-Acid-Lyases; C446529:methylthioalkylmalate synthase 1