Polar bears in the desert

However, many species of plants have developed ways to cope with the higher temperatures. "Unlike animals, many plants can adapt their body shape in response to heat and other environmental factors," says researcher Martijn van Zanten, who is affiliated with Utrecht University and contributed to both publications. “Animals are a completely different story. Simply put, if you place a polar bear in the desert, it will still look like a polar bear in a thick fur coat. But if a plant grows in warmer conditions, it will adapt its body shape accordingly. In this way, the plant tries to function optimally in these less favorable conditions ”.

From compact to open plan form

Many species of plants can adapt the shape of their stems and leaves to make them more resistant to high temperatures. This is also true for the cress thale (Arabidopsis thaliana), considered by many plant biologists as their favorite plant model. In cold conditions, these plants are compact and have their leaves glued to the ground. When temperatures rise, they adopt a more open posture. The leaves, for example, become more upright. This greatly reduces direct radiation from the sun. Also, the leaf stems will stretch out, allowing more wind to pass through the leaves and dissipate heat.

Desired and unwanted stretching

However, in crops and (cut) flowers, this type of stretching is often undesirable. Producers want to control these changes, as stretching can affect product quality. “But at the same time, adaptation is necessary so that crops are more resistant to the high temperatures derived from climate change. This is necessary to maintain production in the long term, ”says Van Zanten.

Make plants more tolerant to the weather

“Many crops have lost the ability to respond well to higher temperatures,” says Van Zanten. "In several crops, it disappeared during the process of domestication and breeding, as breeders focused mainly on other traits."

With climate change increasing temperatures, Van Zanten says there is a growing need to make plants more climate tolerant. “This requires knowledge of how plants cope with higher temperatures. How do they convert the temperature signals they receive into growth adaptations? Investigating the molecular mechanisms by which plants adapt to suboptimal temperatures allows tools to adjust crop architecture through breeding."

The molecular mechanism activates the heat posture.

Cress plants that are no longer adapted to higher temperatures can regain that ability when exposed to certain chemicals. This was discovered by an international research team led by Van Zanten. The team tested a large number of substances on a mutant thale cress that no longer adapts to high temperatures. They found a molecule that can "activate" adaptation to high temperatures in young plants, even at low temperatures.

Researchers call this compound "Heatin." By chemically modifying the molecule and then studying which proteins can bind to the heating, they found a group of proteins called nitrilases. The identified subgroup is known to be found only in cabbages and related species, including watercress.

Together with a plant breeding company, biologists found that cabbage species do indeed respond to warming. They also found that nitrilases are necessary for adaptation to high temperatures, probably because they allow the production of the well-known growth hormone auxin. The researchers published this discovery in The Plant Journal .

New way to adapt to high temperatures

The publication of Heatin's results coincides with another publication, today in Nature Communications. That research was led by scientists from the VIB institute in Belgium, with Van Zanten also involved. The team discovered a previously undescribed protein that regulates the way plants adapt to a warmer environment. The protein was named MAP4K4 / TOT3, with TOT standing for temperature target.

Surprisingly, the TOT3-driven process is largely independent of all the other signaling pathways that biologists have so far linked to heat adaptation in plants. Furthermore, the adaptations of TOT3 do not appear to depend on the amount and composition of light that illuminates a plant.

Van Zanten: “There is a great overlap in the molecular mechanisms by which plants adapt growth to the composition of changing light and high temperatures. With TOT3, we now have a factor at hand with which we can control growth at high temperatures, without interfering with the way the plant handles light. "