Scientists have discovered a previously unknown mechanism by which plants respond to environmental changes: root cells can enter a distinct functional state, activating hundreds of genes associated with adaptation to external conditions. When water is scarce, the proportion of these cells increases significantly. The discovery could help develop more drought-resistant crops.

The study, published in the journal Nature, was conducted by researchers from the Australian Research Council Centre of Excellence in Plants for Space and the School of Molecular Sciences at the University of Western Australia.

Each Cell Type Has Two Functional States

Until now, plant roots have largely been viewed as a collection of clearly defined cell types, each following its own developmental path from a young cell to a mature one. However, an analysis of gene activity in hundreds of thousands of individual cells from the root tips of the model plant Arabidopsis thaliana revealed a more complex picture.

The researchers found that virtually every cell type can be divided into two groups. In one, an additional set of hundreds of genes associated with responses to environmental conditions is activated, while in the other, this genetic program remains inactive.

“We expected each cell type to have its own story, but we found that each has two. The difference is that one group activates an additional set of genes associated with responding to the environment,” explained Dr. Marina Oliva, one of the study's leaders.

This therefore does not involve the formation of new cell types, but rather the existence of two functional states within already known cell types. The scientists described one of them as a distinct environmental response mode.

These Cells Become More Abundant When Water Is Scarce

To find out how the newly discovered mechanism depends on external conditions, the researchers compared plants grown with different levels of water availability. They found that when water was scarce, the proportion of cells activating the additional genetic program increased substantially, from approximately 40% to 67%.

Abscisic acid, a plant hormone involved in coordinating drought responses, plays an important role in this process. Plants unable to produce this hormone or perceive its signals had significantly fewer cells in the environmental response state.

According to the researchers, changes in growing conditions affect not only the activity of individual genes but also the proportions of cells in different functional states. “What was particularly striking was that, when growing conditions changed, the root responded by changing the number of cells that switched on this additional program,” Oliva noted.

Why the Mechanism Went Unnoticed

As Professor Ryan Lister, another leader of the study, explained, previous analytical methods could not reveal this feature because they pooled data from thousands of cells. Averaging the results could conceal differences between individual cells.

The new approach made it possible to examine gene activity at the level of individual cells and discover that even cells of the same type can respond differently to environmental changes. This broadens our understanding of how plants adapt to adverse conditions. Unlike animals, they cannot move to a more suitable environment, so they must adapt their physiology to changes in water and nutrient availability.

“This discovery suggests that one way they adapt is by changing the balance between the two states that cells can adopt, almost like adjusting a switch,” Lister said.

From Agriculture to Growing Plants in Space

Understanding how roots respond to water and nutrient shortages is important for developing crops that can withstand drought. According to the researchers, further investigation of the newly discovered mechanism could help clarify how plants regulate their stress responses and which processes need to be considered when developing more resilient varieties.

The findings could also prove useful for growing plants in controlled environments, particularly on vertical farms and during space missions, where water supply and other environmental parameters must be precisely managed.

However, the discovery does not mean that scientists have already found a way to improve drought resistance in crops. It reveals a previously unknown mechanism of cellular adaptation, further study of which could provide a foundation for developing new approaches to growing plants with limited water resources.