Ancient Metabolic Bypasses Helped Grasses Dominate Landscapes and Agriculture

Researchers at the University of Wisconsin–Madison and collaborating institutions have identified two metabolic innovations that likely helped grasses become dominant across global ecosystems and agriculture. By sequencing the genome of Joinvillea ascendens, a slow-growing relative of grasses found on South Pacific islands, the team compared its metabolic pathways with those of the grass family, Poaceae.

The study, published in Science, shows that all grasses possess two distinct pathways for synthesizing starch, while Joinvillea has only one. This additional starch synthesis route emerged in the common ancestor of grasses roughly 100 million years ago, allowing grass seeds to store roughly twice the energy. Seeds with larger energy reserves can germinate and reach sunlight faster, outcompeting neighboring plants in open habitats.

The team also examined lignin synthesis, a process critical for structural support. Both grasses and Joinvillea possess two lignin pathways, but the researchers traced the origin of this dual system to a period before grasses evolved. They identified two specific DNA mutations that were sufficient to create the second lignin bypass, a discovery that could allow scientists to engineer similar pathways in other plants.

Grasses such as wheat, rice, and maize provide the majority of human caloric intake, yet the metabolic basis for their rapid growth and high productivity has remained unclear. The findings suggest that the combination of enhanced energy storage from dual starch pathways and robust structural support from dual lignin pathways gave early grasses a decisive ecological edge.

Lead researcher Hiroshi Maeda, a professor of botany, said the insights open doors for improving cereal and bioenergy crops. His lab is now exploring how to apply these evolutionary discoveries to increase starch yields, strengthen plant structure, and enhance the sustainable production of nutrients and useful chemicals in agriculture.

Obtaining the genomic data required significant effort: only two of more than 100 Joinvillea seeds germinated, and the plants took two years to grow large enough for sequencing. The project also sequenced three related species to strengthen the comparative analysis.

The research was conducted by an international team including Maeda's postdoctoral researcher Yuri Takeda-Kimura and James Leebens-Mack of the University of Georgia. The paper, "Genomes of Poaceae sisters reveal key metabolic innovations preceding the evolution of grasses," appears in the August 20, 2026 issue of Science.