How Plants Use Proteins to Sense Temperature and Adjust Root Growth

Plants cannot simply move into the shade or switch on a fan. As temperatures climb, they must remain where they are and cope. Their ability to survive rests on how effectively they adapt, particularly below the soil.

Roots continue extending as they seek water and nutrients. When this growth slows down or ceases, the whole plant is put under strain.

Temperature strongly influences the rate at which roots develop. Scientists have long understood that warmer conditions commonly accelerate growth.

What remained uncertain, however, was how plants detect temperature and convert that information into a response. It was something of a black box: a process within the plant was evidently interpreting environmental conditions and directing its actions.

A concealed control system within plant cells

New research has revealed a remarkably straightforward mechanism. Rather than depending solely on altered hormone levels, plants also employ proteins that function as minute sensors within their cells.

These proteins can react directly to changes in temperature, adjusting growth almost immediately.

The finding introduces another dimension to our understanding of plant biology. Instead of creating entirely new molecules, plants can swiftly rearrange components they already possess.

This approach conserves both energy and time, which is particularly important when conditions shift rapidly.

Plant biologist Lucia Strader at the Salk Institute led the research. The study explains how particular proteins associated with a familiar plant hormone enable roots to respond to heat.

The balance of auxin growth signals

Auxin, a hormone governing numerous elements of plant growth, is central to the research. It influences cell expansion, root formation and stem development. Yet auxin does not operate as a straightforward on-off control.

“It has to be just right, because too little or too much can inhibit growth.” noted Strader.

This creates a difficult balance. Higher temperatures generally raise auxin levels while also promoting root growth.

However, elevated auxin levels normally reduce the stretching of root cells. This apparent conflict made scientists question whether another mechanism was at work.

ARF proteins act as thermostats

The explanation involves proteins known as Auxin Response Factors, or ARFs. They determine which genes linked to growth are switched on or off. Researchers were surprised to find that ARFs can themselves detect temperature directly.

In cooler conditions, the proteins remain together in clusters inside the cell. While in this form, they are inactive.

When temperatures increase, the situation changes. The proteins become more stable and disperse from these clusters. Once released, they travel into the cell nucleus, where they activate genes that promote growth.

“You have this reservoir of protein that can be activated depending on the environment, and temperature allows the cell to shift more of that protein into an active form,” said Dr. Edward Wilkinson, first author of the study.

“We think this is something to do with the properties of the protein itself-at higher temperatures, it is more stable and more soluble, so it can readily accumulate and drive temperature responses.”

This mechanism gives plants a rapid response system. They do not have to manufacture fresh proteins; instead, they put proteins already present into action.

“You can think of it as a built-in thermostat within the cell – a very clever way to regulate growth,” said study co-first author Dr. Katelyn Sageman-Furnas.

Why continued root growth is increasingly important

A plant’s roots are its lifeline. They absorb water and nutrients, especially when conditions above the ground become severe.

With changing climate patterns and more frequent heatwaves, roots that can continue growing may determine whether a crop stays healthy or fails.

Knowing how plants register temperature at a molecular level creates new possibilities.

Should scientists be able to direct or modify these internal systems, they might help crops continue growing at higher temperatures. This could bolster food production in areas experiencing increasing heat.

“It’s been known for a long time that plants grow at different rates at different temperatures,” said Strader.

“Now we have discovered this protein that can directly sense temperature and consequently adjust root growth, which is a huge step toward understanding how plants integrate environmental cues into life.”

Collaboration between laboratories

The discovery was not made in isolation. It emerged through collaboration between teams located in different regions of the world.

A connected study took place at the same time, under the leadership of researchers in Argentina. After meeting at a conference, the two groups aligned their work.

“This kind of discovery really represents Salk’s collaborative spirit, and how our culture encourages relationships within and beyond our campus,” said Strader.

“Our cooperation helped optimize resources, getting us closer to understanding plant signaling without competing or wasting time or money.”

Such cooperation accelerated advancement in a field where speed matters. As worldwide temperatures keep rising, findings of this kind could influence how food is produced in the future.

The complete study appeared in the journal Nature Communications.