Desert alga reveals how fast growth and resistance to extreme conditions can coexist

A single-celled green alga from the sand dunes of the Negev Desert has, within just a few years, become a key model organism in modern photosynthesis research. Chlorella ohadii helps researchers better understand plants’ adaptability to extreme environmental conditions. These findings could help make crops more resilient to heat, drought, and other consequences of climate change in the future. Haim Treves, a professor of plant metabolism at RPTU, has been studying the desert alga since its discovery. His findings have now been published in the journal New Phytologist.

Scorching sun, daytime highs reaching 60 degrees Celsius (140 degrees Fahrenheit), nighttime temperatures dropping below freezing and water available only in the form of dewdrops for a short time in the morning: The conditions in the Negev Desert, a rocky and sandy landscape in southern Israel, seem hostile to life. Yet there are organisms that have developed strategies to survive and thrive there. Among them is the green alga Chlorella ohadii, which professor Itzik Ohad—Haim Treves’ mentor—isolated from the desert’s biological soil crust over a decade ago.

This discovery has given new impetus to research on photosynthesis—the central process that plants, algae and phototrophic bacteria use to produce sugar from water and carbon dioxide with the help of sunlight.

“Although photosynthesis is one of the most thoroughly studied processes, we still do not fully understand what limits the growth of photosynthetic organisms and why some grow faster than others. Looking at the Negev Desert, one of the harshest environments on Earth, we assumed that anything that survives there could help us better understand the potential and limitations of photosynthesis and develop more resilient crops for the future,” explains Treves.

Robust, fast-growing and super-efficient

Chlorella ohadii offers numerous avenues for research in this regard. It is resistant to numerous stress factors, including extremely intense light, dehydration and high temperatures. “As you’d expect from a desert alga, it continues to grow and photosynthesize even under light intensities twice as high as those of full sunlight. What’s astonishing is that it achieves growth rates that no other phototrophic organism—one that uses sunlight as an energy source—can match. At the same time, it uses sunlight particularly effectively for photosynthesis,” says the plant researcher.

Until now, scientists assumed that an organism could either be particularly resilient or grow well under optimal conditions—but not both. The desert alga, which refutes this dogma, is thus an ideal research model for questions concerning energy production, metabolic processes and how organisms cope with environmental stress.

Harnessing the properties of Chlorella ohadii

Through detailed physiological, biochemical and molecular biological studies, Treves has uncovered what makes this robust alga so efficient and fast. Extensive genomic, protein and metabolic analyses provided valuable insights into the mechanisms that enable its extraordinary growth and high resilience.

“One example is its exceptionally high metabolic rates. In the desert, the green alga has less than an hour each morning to grow. It must react quickly and flexibly to changing conditions. It achieves this because the light-driven redox reactions proceed at lightning speed,” explains the researcher.

Treves and his team are testing the promising genes, structures and traits they’ve discovered in Chlorella ohadii on model and crop plants. The goal: to increase yields. “We’re currently in the process of patenting a metabolically modified plant that exhibits traits similar to those of the desert alga and whose seed yield has been increased by 30%. This is how we’re harnessing the potential of this tiny alga to help secure our food supply,” Treves says.

In addition, the researchers are developing specialized tools to quantify the metabolic rates that underlie the unique properties of Chlorella ohadii. “The tools for performing metabolic flux analysis are available only here and at a handful of other research institutes.”

Who’s behind this story?

Gaby Clark

MA in English, copy editor since 2021 with experience in higher education and health content. Dedicated to trustworthy science news.

Full profile →

Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

Full profile →