Tag Archives: Atacama desert

Scientists find ‘genetic goldmine’ in driest place on Earth that may boost crop resilience

The Atacama Desert. Credit: Pixabay.

For years, Chilean researchers have collected plant samples from the Atacama Desert and sequenced their DNA in an effort to understand how, against all odds, they’re able to withstand one of the harshest places on Earth. In a new study, the scientists have reported a range of genes that have enabled these hardy plants to flourish with no rainwater — and which, in the future, may help our food crops cope with increasingly dried climates.

Life finds a way even in a Mars-like environment

The Atacama Desert in Chile stretches across a roughly 600-mile (1,000-kilometer) tract of land wedged between the coastal Cordillera de la Costa mountain range and the Andes Mountains, an unusual topography that blocks rainfall from the east and prevents the formation of clouds of rain. The annual rainfall across the Atacama is only 15 millimeters, which makes it the driest place on Earth by far. Some parts of the desert see rain only once in a couple of centuries and its extreme arid landscape has made it a film director’s favorite place to shoot movies about Mars.

But even though the Atacama Desert sounds like a hell hole, there are some plants that have found a way to cope with the extreme dryness, high altitude, poor nutrient soil, and excessive radiation from the sun. These are generally small, deep-rooted, thorny plants that can reach deep underground to capture some of the moisture found there. These include the saltbush, tufted grass, buckwheat bush, black bush, ‘tola’ shrubs, rice grass, ferns, little leaf horsebrush, black sage, and chrysothamnus.

For the last decade, Rodrigo Gutiérrez, professor in the Department of Molecular Genetics and Microbiology at Pontificia Universidad Católica de Chile, has collected plants from 22 different sites covering a wide range of vegetation and elevations. For each sample, Gutiérrez and colleagues recorded a variety of factors, such as temperature, radiation levels, soil quality, and water content.

This characterization for each sample, along with DNA sequencing, allowed the researchers to assemble a genetic profile for 32 of the most important plant species in the Atacama. The analysis also assessed the plant-associated soil microbes based on these DNA sequencing, showing that some of the plants developed symbiotic bacteria near their roots that optimize the intake of nitrogen, a critical nutrient for plant growth that is severely lacking in this desert.

Researchers collected, labeled, and froze plant samples from the Atacama, then shipped them more than 1,000 miles (1,600 km) to be processed for RNA extraction. Credit: Melissa Aguilar.

Colleagues at New York University led by Gloria Coruzzi from the Department of Biology and Center for Genomics and Systems Biology identified the specific genes that are associated with adaptations in the Atacama plants by comparing the 32 desert plants with 32 non-adapted but genetically similar “sister” species.

“The goal was to use this evolutionary tree based on genome sequences to identify the changes in amino acid sequences encoded in the genes that support the evolution of the Atacama plant adaptation to desert conditions,” said Coruzzi.

Beefing up food crops

This state-of-the-art genetic analysis pinpointed 265 genes whose protein sequence may have been selected by evolutionary forces, forged by millions of years of life in the harsh Atacama desert. These include genes involved in photosynthesis that may allow the plants to cope with the high radiation, as well as those involved in the regulation of stress, salt, and metal ions, which may explain how the plants can grow in the nutrient-poor soil.

“Our study of plants in the Atacama Desert is directly relevant to regions around the world that are becoming increasingly arid, with factors such as drought, extreme temperatures, and salt in water and soil posing a significant threat to global food production,” said Gutiérrez, who likens the findings to a “genetic goldmine”.

Some of the Atacama plants are related to staple crops, such as grains, legumes, and potatoes. As such, these newly identified candidate genes could be used to engineer more resilient crops and improve our food security in the face of increased desertification of the planet.

The findings appeared in the journal Proceedings of the National Academy of Sciences.

A rover mission drilled 80 cm below the surface of the Atacama desert and found unusual organisms. Credit: NASA.

NASA trains to search for Martian life in world’s driest desert

A rover mission drilled 80 cm below the surface of the Atacama desert and found unusual organisms. Credit: NASA.

A rover trial mission drilled 80 cm below the surface of the Atacama desert and found unusual organisms. Credit: Stephen B. Pointing.

The Atacama Desert in Chile is not only the driest but also the oldest desert on Earth. It’s so dry that in some parts — like its hyper-arid core — there has been no recorded rainfall for hundreds of years. What’s more, the soil is very salty and exposed to high doses of UV radiation. That all sounds a lot like Mars, and, for years, NASA has been testing many of its emerging technologies here before deploying them in the field, on the red planet.

One of the most recent of such missions deployed a robotic rover to the desert, where it sampled subsurface soil and discovered unusual microbes. The life forms found in the samples were sparsely distributed due to low water and nutrient availability, but also because of the soil’s unique chemistry.

“We have shown that a robotic rover can recover subsurface soil in the most Mars-like desert on Earth,” Stephen Pointing, a Professor at Yale-NUS College, Singapore, who led the study, said in a statement. “This is important because most scientists agree that any life on Mars would have to occur below the surface to escape the harsh surface conditions where high radiation, low temperature and lack of water make life unlikely.”

In just a year, in 2020, both NASA and the European Space Agency (ESA) will start deploying rovers on the surface of Mars. Their mission will be to look for evidence of past or present life, which means drilling to significant depth beneath the surface.

The autonomous rover deployed in the Atacama Desert successfully drilled down to a depth of 80cm to recover sediment samples. These samples were compared to those carefully collected by hand. Researchers used DNA sequencing to study the microbes found in the samples, finding that both sets contained very similar organisms.

“We found microbes adapted to high salt levels, similar to what may be expected in the Martian subsurface. These microbes are very different from those previously known to occur on the surface of deserts,” Pointing said.

Closeup of the drill used in the Mars-like Atacama desert. Credit: Stephen B. Pointing.

Closeup of the drill used in the Mars-like Atacama desert. Credit: Stephen B. Pointing.

According to the authors, if there’s any microbial life on Mars, it will likely exhibit similar characteristics to that found in Earth’s most extreme habitats. Patchiness is one such characteristic, which means that detection will prove to be challenging. In fact, previous research was unable to recover DNA from any depth of Atacama’s hyper-arid core, suggesting that it was lifeless. The findings show that there is indeed life even in such an inhospitable environment — you just have use very sensitive tools to find it.

In the future, researchers plan on drilling even deeper to see just how far down microbes can go in one of the most inhospitable places on Earth.

Finding life on Mars — if there’s any at all — won’t be a piece of cake. It was challenging enough detecting organisms in the Atacama, which is teeming with life on its surface despite the inhospitable conditions. Another limitation is that DNA sequencing was performed in the lab with sophisticated methods. On Mars, it will have to be done on-site by the rover which presents its own unique set of technical challenges.

“Mars missions hope to drill to approximately 2m and so having an Earth-based comparison will help identify potential problems and the interpretation of results once rovers are deployed there. Ecological studies that help us predict the habitable areas for microbial communities in Earth’s most extreme environments will also be critical to finding life on other planets,” Pointing said.

The findings appeared in the journal Frontiers in Microbiology.

Credit: Pixabay.

Dry irony: first rain in centuries causes extinction of Atacama Desert microbes

Credit: Pixabay.

Credit: Pixabay.

The Atacama Desert is not only the driest but also the oldest desert on Earth. It’s so dry that in some parts — like its hyper-arid core — there has been no sign of rain recorded for 500 years. You’d think that a bit of rain would be a godsend the few creatures that live there. But for many microbial species that have become adapted to living almost without any water, recent rainfall that penetrated the hyper-core spelled their doom. However, on the upside, we now know a bit more about what hypothetical creatures living on Mars in similar conditions might have experienced during the Red Planet’s rich geological history, according to a new study published in Scientific Reports

When water in the desert is actually a bad thing

The Atacama Desert in northern Chile is a (typically) rainless plateau that covers almost a 600-mile area. It’s 50 times drier than Death Valley and the average rainfall there is just one millimeter per year. In the early 20th century not one single drop of rain reached Atacama’s surface for 173 months. In fact, it’s so dead, barren and alien that NASA regularly conducts tests here simulating conditions on Mars.

For millions of years, regions of the Atacama Desert have remained hyperarid. But even in such inhospitable conditions, some surface soil microbial species have adapted to survive with meager amounts of liquid water. However, researchers from the Center for Astrobiology (CAB) at the Universidad Autónoma de Chile found that recent unexpected rainfall caused many microbial species to quickly perish from the osmotic shock caused by the sudden abundance of water.

According to the researchers, the extinction range reaches 85%, wiping out all archaea and eukaryotes. Only a handful of bacteria, such as a newly identified species of Halomonas, remain metabolically active and are able to reproduce in the lagoons. The rains have been attributed to changing climate over the Pacific Ocean.

“Our group has discovered that, contrary to what could be expected intuitively, the never-before-seen rainfall has not triggered a flowering of life in Atacama, but instead, the rains have caused enormous devastation in the microbial species that inhabited the region before the heavy precipitations,” Dr. Alberto G. Fairén, lead author of the new study, said in a statement.

The findings are important in the context of the astrobiological exploration of Mars, a hyperarid planet that experienced catastrophic floodings in ancient times. During the Red Planet’s early days, in a period called the Noachian (4.5-3.5 billion years ago), its surface used to to be richly covered in water, not at all that different from Earth. This is an undisputed fact among researchers, judging from hydrogeological evidence present on the Martian surface such as hydrated minerals, and geological formations such as dried rivers, lakes, deltas, and a huge basin that looks like an ocean in the northern plains.

An artist’s impression of what ancient Mars may have looked like, based on geological data. Image by Ittiz.

After this ‘wet’ period, which looks like it could have easily supported life, Mars lost its atmosphere and hydrosphere.

“But at times during the Hesperian period (from 3.5 to 3 billion years ago), large volumes of water carved its surface in the form of outflow channels, the largest channels in the solar system. If there were still microbial communities withstanding the process of extreme drying, they would have been subjected to processes of osmotic stress similar to those we have studied in Atacama,” Fairén said.

When liquid water resurfaced on Mars, it might have actually killed any pockets of life that may have survived submerged deep under the soil, these new findings seem to suggest.

 

El Niño turned the driest place on Earth into a colourful ocean of life

You wouldn’t usually describe the Atacama desert — the driest place on Earth — as vibrant with life and colourful. Far from it. For the second time this year, however, the desert bloomed as thousands of dormant species of flowers and plants awoke after El Niño brought a rainy boom to the region.

The Atacama Desert in Chile is a (typically) rainless plateau that covers almost a 600 mile location that’s 50 times drier than Death Valley. The average rain fall in the region is just one millimeter per year and in the early 20th century not one single drop of rain reached Atacama’s surface for 173 months. In fact, it’s so dead, barren and, well, alien that NASA regularly conducts tests here simulating conditions on Mars.

Atacama isn’t quite dead, and if anything it’s quite a testimony to the resilience of life. Beneath the sterile soil lie dormant flower bulbs and rhizomes which explode when give the opportunity. This is what happened very recently when a new gush of rainfall swept the area driven by  El Niño – a band of anomalously warm ocean water temperatures that periodically develop off the Pacific coast of South America causing pattern of extreme weather events. Floods and droughts are regular in the onset of  El Niño which surfaces every couple of years or so. This year’s  El Niño is poised to be the strongest since 1950.

“When you think of the desert, you think of total dryness, but there’s a latent ecosystem here just waiting for certain conditions to arise,” said Raul Cespedes, a desert specialist at the University of Atacama.

Atacama desert

Image: EPA

In March, heavy rains caused floods in the vicinity which tragically killed 30 people. It also caused a massive bloom. The desert is now blooming for the second time this year, which makes it quite the anomaly.

“Two flowerings a year is very unusual in the most arid desert in the world, and that’s something we’ve been able to enjoy this spring, along with people from all over the world. There’s a lot of interest in seeing it,” said Daniel Diaz, director of the National Tourism Service for Atacama region.

White-peaked volcanos rise from the plains of the Atacama Desert under deep blue skies. The Atacama is the driest desert in the world.

32 inches of snow in the driest place on Earth

A bit late on reporting this, but I’m still struck with amazement by this extremely peculiar case of precipitations. Last week a cold wave hit Chile and surroundings, including the Atacama desert, known to be the driest place on Earth, covering it in snow.

In this area less than 50mm of rain on average is reported each year, and in some spots it can be as low as 1-3 mm. It’s extremely surprising then that the Atacama has been inflicted with 31.5 inches of snow after a cold front brought subzero temperatures to much of South America.According to the national emergency centre in Chile, the area had not seen this amount of snow in close to 20 year, leading to closed roads and stuck vehicles. According to local media, authorities rescued 36 people on Tuesday, whose bus had been stuck in heavy snow.

Parts of the desert are known to be devoid of moisture and therefore all life, even bacteria. The lack of airborne water and minimal population leads to it having some of the clearest skies in the world, hence the abundance of huge observatories as they can stargaze all year round.

White-peaked volcanos rise from the plains of the Atacama Desert under deep blue skies. The Atacama is the driest desert in the world.

White-peaked volcanos rise from the plains of the Atacama Desert under deep blue skies. The Atacama is the driest desert in the world.

Global warming? Might be. Freak of nature? Weather is known to act unpredictably all the time. What’s your take?