Garden Science: A Plant’s Built-In Thermostat

by Rhonda Bassel-Duby, Ph.D., CCMGA Intern

When it's hot outside, we can head indoors or find some shade. Plants don't have that option because they are rooted in place. To make matters worse, heat dries out the soil and speeds up water evaporation, putting plants at risk of running out of water. Fortunately, plants have evolved a clever survival strategy: when temperatures rise, they grow their roots deeper and wider to reach water and nutrients elsewhere in the soil.

Figure 1. Illustration showing that in warmer temperatures plants grow longer stems and roots compared to in cooler temperatures. This process is controlled by Auxin Response Factors (ARFs). In cooler temperatures, ARFs are clustered and inactive. As the temperature increases, ARFs are activated and switch on genetic programs to promote plant growth. ARFs act like a thermostat to trigger growth. Illustration courtesy of Professor Lucia Strader, Salk Institute. Used with permission.

How do plants sense temperature?

Two research groups, one at Duke University and the other at the University of Buenos Aires, recently discovered a built-in "thermostat" in plants. Both teams published back-to-back studies identifying the molecular components behind this system. They found that a family of proteins called Auxin Response Factors (ARFs) act as an internal temperature sensor that triggers root growth.

How does this built-in thermostat work?

ARF proteins are present in plant cells at all times, but they only spring into action when activated. At cooler temperatures, ARF proteins sit inactive, clustered together, and nonfunctional. As the temperature climbs, they shift into a soluble, active form. Once activated, ARF proteins switch on genetic programs that drive root growth by increasing cell division, helping cells transition into the root's growth zone, and extending the time cells spend elongating.

In short, plant cells keep a ready reserve of ARF proteins on standby, like a thermostat waiting to click on, so they can quickly extend their roots when the heat turns up.

Why is this important to gardeners?

Keeping plants healthy through heat stress is a constant challenge for gardeners and farmers alike. Extended root growth is what allows plants to keep finding water and nutrients during hot spells, which is essential to their survival. This discovery gives scientists a new approach for breeding or engineering plants that can better withstand extreme heat. Developing plants that are more heat resistant would be an asset to home gardeners. Additionally, the availability of heat-resistant crops could protect our food supply as climate stress increases. These findings open a promising new path for boosting gardening outcomes and crop resilience in a warming world.

Want to learn more?
Download the Beat the Heat: Summer Lawn Care Guide presentation by Dr. Becky Bowling, Texas A&M AgriLife Extension, for additional tips, illustrations, and lawn care recommendations.

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Research Source:
This article is based on two companion studies published in Nature Communications in March 2026 describing the discovery of a temperature-sensitive mechanism involving Auxin Response Factors (ARFs).

Nature Communications, March 2026
DOI: 10.1038/s41467-026-71012-y
DOI: 10.1038/s41467-026-71011-z

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Our new Garden Science series translates current horticultural research into practical information for home gardeners. Each article highlights recent scientific discoveries and explains what they may mean for your garden.