Evolution of chemical diversity in plants
Plants produce an astonishing diversity of various chemicals. So far, more than 200,000 different plant metabolites have been described. Individual specialized metabolites help plants cope with detrimental abiotic factors or defend themselves against natural enemies, such as herbivores and pathogens. While we understand the functions of some of these metabolites in plants, we still seek explanations for their seemingly excessive diversity.
In their current publication in Ecology Letters, Martin Volf and his team show how different selection pressures support the evolution of different aspects of plant chemical diversity. The team studied willow species growing at different elevations and applied novel metabolomics tools to explore the diversity of metabolites they produce. Their results show that plants at different elevations opt for different chemical strategies that allow them to cope best with the type of stress they experience. At high elevations, all willow species are chemically similar and produce structurally related antioxidants that help them withstand the detrimental abiotic conditions, such as high UV irradiation. In contrast, lowland willow species tend to evolve more variable chemical profiles. Many insect herbivores that occur at low elevations are adapted to willow defences and prefer to feed on hosts that are chemically similar. Being chemically more variable thus probably helps lowland willows avoid sharing their natural enemies. Overall, these trends contribute to various aspects of chemical diversity and jointly give rise to the astonishing richness of metabolites we observe in the plant kingdom.
Volf M., Leong J. V., de Lima Ferreira P., Volfová T., Kozel P., Matos-Maraví P., Hörandl E., Wagner N. D., Luntamo N., Salminen J.-P., Segar S. T., Sedio B. E. (2023): Contrasting levels of β-diversity and underlying phylogenetic trends indicate different paths to chemical diversity in highland and lowland willow species. Ecology Letters, DOI: 10.1111/ele.14273