Molecular Ecology and Evolution
Zapata, Felipe , Fine, Paul .
A molecular perspective on plant chemical defense evolution: Molecular evolution of monoterpene synthases in Protium (Burseraceae).
The coevolutionary arms race hypothesis (CARH) states that the selective pressure of herbivores on plant species is largely responsible for the vast diversity of plant secondary metabolites, and thus it predicts that variation of plant chemical defenses should be under diversifying selection, and associated with plant speciation events. Although some studies have analyzed the evolution of plant defense chemistry in relation to herbivore phylogenies, none has evaluated variation in plant chemistry and the genes underlying this variation at the genus level. In the tropical tree genus Protium (Burseraceae), terpenes are a major component in the blend of diverse secondary metabolites that likely contribute to resistance against insect herbivores. For a set of species from across the Protium phylogeny, we characterized terpene chemical profiles and variation in monoterpene synthases (TPSb), the genes controlling a fundamental step in monoterpene biosynthesis. Preliminary analyses reveal i) considerable interspecific variation in composition and concentration of leaf terpenes, ii) evidence for excess of nonsynonymous substitutions on TPSb genes concentrated in few codons, and iii) variable selection levels along the TPSb phylogeny, with support for positive selection along few branches representing different species or speciation events. These initial results are partially consistent with the predictions of the CARH. We believe that our results, in conjunction with common garden experiments, transcription profiling, heterologous expression, and genomic scans will be a powerful approach to fully elucidate the mechanistic basis underpinning the co-evolutionary processes driving species diversification.
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1 - University Of California, Department Of Integrative Biology, 3060 Valley Life Sciences Bldg. #3140, Berkeley, CA, 94720-3140, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Westminster Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 4:30 PM