Positive selection driving diversification in plant secondary metabolism
- Markus Benderoth†,
- Susanne Textor‡,
- Aaron J. Windsor†,§,
- Thomas Mitchell-Olds†,§,
- Jonathan Gershenzon‡, and
- Juergen Kroymann†,¶
- Department of †Genetics and Evolution and
- ‡Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany
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Edited by John F. Doebley, University of Wisconsin, Madison, WI, and approved April 25, 2006 (received for review March 2, 2006)
Abstract
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.
Footnotes
- ¶To whom correspondence should be addressed. E-mail: kroymann{at}ice.mpg.de
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↵ §Present address: Department of Biology, Duke University, Durham, NC 27708.
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Author contributions: J.K. designed research; M.B. and J.K. performed research; S.T. and A.J.W. contributed new reagents/analytic tools; M.B. and J.K. analyzed data; and T.M.-O., J.G., and J.K. wrote the paper.
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Conflict of interest statement: No conflicts declared.
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This paper was submitted directly (Track II) to the PNAS office.
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Data deposition: The sequences reported in this paper have been deposited in the EMBL database (accession nos. AM180569–AM180585).
- Abbreviations:
- MAM,
- methylthioalkylmalate synthase.
Abbreviation:
- © 2006 by The National Academy of Sciences of the USA
