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Open Access Highly Accessed Research article

Adaptive evolution of the chrysanthemyl diphosphate synthase gene involved in irregular monoterpene metabolism

Ping-Li Liu13, Jun-Nan Wan1, Yan-Ping Guo2, Song Ge3 and Guang-Yuan Rao1*

Author Affiliations

1 College of Life Sciences, Peking University, Beijing, 100871, China

2 College of Life Sciences, Beijing Normal University, Beijing, 100875, China

3 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China

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BMC Evolutionary Biology 2012, 12:214  doi:10.1186/1471-2148-12-214

Published: 8 November 2012

Abstract

Background

Chrysanthemyl diphosphate synthase (CDS) is a key enzyme in biosynthetic pathways producing pyrethrins and irregular monoterpenes. These compounds are confined to plants of the tribe Anthemideae of the Asteraceae, and play an important role in defending the plants against herbivorous insects. It has been proposed that the CDS genes arose from duplication of the farnesyl diphosphate synthase (FDS) gene and have different function from FDSs. However, the duplication time toward the origin of CDS and the evolutionary force behind the functional divergence of the CDS gene are still unknown.

Results

Two duplication events were detected in the evolutionary history of the FDS gene family in the Asteraceae, and the second duplication led to the origin of CDS. CDS occurred after the divergence of the tribe Mutisieae from other tribes of Asteraceae but before the birth of the Anthemideae tribe. After its origin, CDS accumulated four mutations in sites homologous to the substrate-binding and catalysis sites of FDS. Of these, two sites were involved in the binding of the nucleophilic substrate isopentenyl diphosphate in FDS. Maximum likelihood analyses showed that some sites in CDS were under positive selection and were scattered throughout primary sequences, whereas in the three-dimensional structure model they clustered in the large central cavity.

Conclusion

Positive selection associated with gene duplication played a major role in the evolution of CDS.