7 Chemotaxonomy Seen from a Phylogenetic Perspective and Evolution of Secondary Metabolism

Annual Plant Reviews book series, Volume 40: Biochemistry of Plant Secondary Metabolism
Michael Wink

Michael Wink

Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany

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Flavia Botschen

Flavia Botschen

Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany

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Christina Gosmann

Christina Gosmann

Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany

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Holger Schäfer

Holger Schäfer

Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany

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Peter G. Waterman

Peter G. Waterman

Retired from Centre for Phytochemistry, Southern Cross University, NSW, Australia

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First published: 19 April 2018
Citations: 7
This article was originally published in 2010 in Biochemistry of Plant Secondary Metabolism, Volume 40 (ISBN 9781405183970) of the Annual Plant Reviews book series, this volume edited by Michael Wink. The article was republished in Annual Plant Reviews online in April 2018.

Abstract

All plants produce secondary metabolites (SM); however, the structural types are often specific and restricted to taxonomically related plant groups. This observation was the base for the development of ‘chemotaxonomy’. A closer look indicates that a number of SM have a taxonomically restricted distribution. Very often, we also find the same SM in other plant groups which are not related in a phylogenetic context. Examples are given for several groups of alkaloids (including pyrrolizidine and quinolizidine alkaloids) and for cardiac glycosides. How to explain the patchy distribution? Theoretically, the occurrence of SM in unrelated taxa may be due to convergent evolution. Alternatively, the genes encoding the enzymes of secondary metabolism might be widely distributed in the plant kingdom, but switched on or off in a certain context. The analysis of nucleotide and amino acid sequences, which were generated in numerous genome projects during the past decades, provides evidence that most of the genes which encode key enzymes of SM formation have indeed a wide distribution in the plant kingdom. Examples discussed are tryptophan decarboxylase, tyrosine decarboxylase, phenylalanine ammonia-lyase, chalcone synthase, strictosidine synthase, berberine bridge enzyme and codeine reductase. It is speculated that these genes were introduced into the plant genome by horizontal gene transfer, i.e. via bacteria that developed into mitochondria and chloroplasts. Evidence is presented that a patchy distribution can also be due to the presence of endophytic fungi, which are able to produce SM (e.g. ergot alkaloids in Convolvulaceae). The evolution of plant secondary metabolism is a complex process that took place over the past 500 million years.

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