The new study published in Plants, People and Planet has identified that certain plants were born with a biological starter kit of genes that allowed them to evolve a turbo-charged form of growth known as C4 photosynthesis. While most plants struggle to grow in high temperatures, C4 plants - such as maize and sugarcane - use a specialised internal system to concentrate carbon dioxide, allowing them to thrive in heat while using significantly less water.
The team led by Dr Luke Dunning created the first high-quality DNA maps for an ancient group of grasses called the Aristidoideae, allowing them to look back in time at the genetic blueprint of these plants. They found that these super-efficient grasses did not become resilient by accident; instead, their ancestors underwent a genetic makeover millions of years before the heat-resistant traits even appeared.
By sequencing this ancient grass lineage, the study found that certain species were naturally predisposed to survive heat through the opportunistic use of pre-existing genetic diversity. These plants gained an extra copy of a core enzyme, beta-carbonic anhydrase, alongside early genetic changes that improved how they move nutrients and manage stress. These modifications created a biological foundation that allowed this specific family to repeatedly evolve more efficient photosynthesis, while other vital staples like rice and wheat remained restricted by their ancestral DNA.
We have traced the deep evolutionary origins of the efficient C4 photosynthetic system, showing that early genetic changes laid the foundation for a major biological innovation. These insights help explain how complex traits evolve, and why they emerge in some lineages but not in others.
Dr Lara Pereira
Co-author
By identifying the specific genes that represent these ancient pre-adaptations, the study provides a roadmap for how scientists might be able to control adaptations of other crops. Understanding these genetic foundations moves us closer to ensuring food security by allowing researchers to potentially develop more efficient, natural ways for plants to thrive on a warming planet.