When drought sets in on the African savannah, almost all the trees freeze in anticipation of rain. But one of them behaves in the opposite way – instead of slowing down, it begins to actively grow. A scientific explanation has been found for this amazing property of the umbrella acacia (Vachellia tortilis).

This hardy, flat-topped tree is a true survivalist. While other plants save moisture, umbrella acacia, on the contrary, accelerates its growth and continues photosynthesis.

It was this all-in strategy that helped her survive for centuries in one of the harshest places on the planet. The study was published in the journal Plant Journal.

Rare exception

Most plants act in a standard way during drought – they seem to “close” in order to conserve precious water. Acacia umbrella does exactly the opposite.

Scientists compared it to its relative, the magnificent thorny acacia (Vachellia robusta), which prefers wetter areas. The difference was striking. The relative behaves economically, but the umbrella acacia, on the contrary, tries to grow actively and absorb carbon.

The ability of this tree to live in spite of everything is simply amazing. It is eaten by giraffes, broken by elephants, and has to compete with grass, which also regularly burns. Its main advantage is its powerful root system, which forms very early.

“If you dig up a small seedling, you will see that it has roots like a mature tree,” said evolutionary biologist James Pease from Ohio State University (USA). “And once he gets the right amount of water, he already has a ready-made system that can support a full-fledged tree.”

Genetic secret

Scientists also studied the genetic response of trees to drought. It turned out that both types of acacia use similar tools to deal with stress, but they use them differently. The magnificent acacia plays defense – slowly and carefully.

Her umbrella relative is on the attack, aggressively and without looking back. The difference lies not in the genes themselves, but in when and how they are activated.

This discovery is important not only for understanding life on the savannah. The problem of drought and climate change affects the whole world, and until now there has been very little genomic research on tropical trees. Understanding how some species adapt to extreme conditions could help scientists conserve nature and even develop drought-resistant crops.