An international research team has published the first comprehensive genome assembly of Ilex paraguariensis — the source plant for yerba mate — in the peer-reviewed journal eLife on January 8, 2025. The study, which involved collaborators from the University of Illinois and institutions across South America, resolves a long-standing question in plant evolutionary biology: how did three of the world's most widely consumed caffeinated beverages — coffee, tea, and yerba mate — each evolve the ability to produce the same psychoactive alkaloid?
Convergent Evolution, Not Common Ancestry
The answer, the researchers demonstrate, is convergent evolution — the independent emergence of the same trait in unrelated lineages. While coffee (Coffea arabica) and tea (Camellia sinensis) are both members of the Asterids, a large clade of flowering plants, yerba mate belongs to an entirely separate group: the order Aquifoliales. The genome data reveals that the enzymes responsible for caffeine synthesis in yerba mate are structurally and evolutionarily more similar to those found in cacao trees (Theobroma cacao) and Paullinia flowering shrubs — both Rosid species — than to the XANTHOSINE METHYLTRANSFERASE (XMT) enzymes used by coffee and tea.
This finding means that nature arrived at caffeine production through at least two fundamentally different enzymatic pathways. In coffee and tea, caffeine synthesis proceeds through a well-characterized three-step methylation cascade involving a specific family of N-methyltransferases. In yerba mate, the genome data suggests that a distinct set of duplicated genes was co-opted for caffeine production — genes that are not homologous to their functional counterparts in Coffea or Camellia.
A 50-Million-Year-Old Genome Duplication
The study also uncovered evidence that an ancestor of modern Ilex paraguariensis underwent a whole-genome duplication event approximately 50 million years ago — a cataclysmic doubling of the entire genetic blueprint. Whole-genome duplications are recognized as engines of evolutionary innovation because they provide 'spare copies' of every gene, freeing duplicates to acquire new functions without compromising essential processes. The researchers propose that this ancient duplication event provided the raw genetic material from which the yerba mate caffeine pathway was eventually assembled.
The yerba mate plant actually deleted the genes that are most similar to the ones coffee uses for caffeine production, and then adapted completely different duplicated genes to produce caffeine instead. It's a remarkable example of evolutionary creativity.
Agricultural Applications
Beyond its evolutionary significance, the genome assembly opens practical possibilities for yerba mate agriculture. With a complete genetic map, breeders can now identify markers for desirable traits — caffeine content, drought tolerance, pest resistance, and flavor-associated metabolites — and develop improved cultivars through marker-assisted selection rather than slow conventional breeding. The researchers suggest that the genome could enable the development of naturally decaffeinated yerba mate varieties, a product category that currently does not exist commercially but for which consumer demand is anticipated to grow.