A new study has identified metabolic traits that may help explain how grasses evolved to dominate natural ecosystems and become some of the world’s most important food crops.
Researchers led by plant biologists Hiroshi Maeda of the University of Wisconsin-Madison and James Leebens-Mack of the University of Georgia found that grasses have two pathways for producing starch, while closely related non-grass plants have only one, The Scientist reported.
The findings, published in Science, could also open new possibilities for developing crops with higher energy content and stronger plant structures.
Grasses, which include maize, rice and wheat, account for more than 40% of the calories consumed by people worldwide. To investigate their evolution, the researchers sequenced four plant species: one grass, Pharus latifolius, and three closely related non-grasses, Joinvillea ascendens, Ecdeiocolea monostachya and Typha latifolia.
The team found that all plants can produce starch inside plastids, structures involved in producing energy and other molecules. Grasses, however, can also synthesise starch in the cytosol, the fluid portion of plant cells.
Analysis of 20 gene families involved in cytosolic starch production indicated that this second pathway emerged following a whole-genome duplication event in the common ancestor of grasses.
Researchers said the additional starch pathway may have helped grasses gain an advantage in open environments with abundant sunlight, while also contributing to their agricultural value.
The study also examined lignin, a major component of plant biomass that provides structural support and helps plants transport water and resist pests.
Scientists found that grasses and their closely related non-grass species possess genes for two lignin-production pathways. A duplicated gene for phenylalanine ammonia lyase (PAL) evolved into a related enzyme called phenylalanine/tyrosine ammonia lyase (PTAL), allowing plants to produce lignin from additional amino acids.
Further analysis identified two amino acid changes that were sufficient to alter PAL activity into PTAL activity.
The researchers said these mutations could potentially be introduced into other plants to create an additional lignin-production pathway.
The findings could eventually help scientists develop crops with enhanced starch production for greater energy content and increased lignin for improved strength and resilience, offering new possibilities for agricultural and plant biotechnology research.
