Scientists find ‘genetic gold mine’ in the driest place on Earth, which may increase crop resilience

The Atacama Desert. Credit: Pixabay.

For years, Chilean scientists have been collecting plant samples from the Atacama Desert and sequencing their DNA in an attempt to understand how, against all odds, they are able to withstand one of the toughest places on Earth. In a new study, researchers have reported on a number of genes that have enabled these hardy plants to bloom without rainwater – and which in the future can help our food crops cope with an increasingly dry climate.

Life finds a way even in a Mars-like environment

The Atacama Desert in Chile stretches over some 600 miles (1,000 kilometers) of land wedged between the coastal Cordillera de la Costa mountain range and the Andes Mountains, an unusual topography that blocks precipitation from the east and prevents the formation of clouds of rain. The annual rainfall over the Atacama is only 15 millimeters, making it the driest place on Earth. Some parts of the desert only see rain 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 altitudes, poor nutrients and excessive radiation from the sun. These are generally small, deeply rooted, thorny plants that can reach deep underground to capture some of the moisture found there. These include salt shrub, tufted grass, buckwheat shrub, black shrub, ‘tola’ shrubs, rice grass, ferns, small leaf horse brush, black sage and chrysothamnus.

Over the past decade, Rodrigo Gutiérrez, Professor at the Department of Molecular Genetics and Microbiology at the Pontificia Universidad Católica de Chile, has collected plants from 22 different locations covering a wide range of vegetation and heights. For each sample, Gutiérrez and colleagues recorded a number 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 major plant species in 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, optimizing the uptake of nitrogen, a critical nutrient for plant growth that is severely deficient in this desert.

Researchers collected, labeled and froze plant samples from Atacama and then sent 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 of the Department of Biology and the Center for Genomics and Systems Biology identified the specific genes associated with adaptations in the Atacama plants by comparing the 32 desert plants with 32 non-adapted but genetically similar “sisters. “art.

“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 development of the Atacama plant’s adaptation to desert conditions,” Coruzzi said.

Increase in food crops

This advanced genetic analysis pointed to 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 can enable the plants to cope with the high levels of radiation, as well as those involved in the regulation of stress, salt and metal ions, which may explain how the plants can grow in it. nutrient-poor soils.

“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. , which compares the results to a “genetic gold mine”.

Some of the Atacama plants are related to basic crops, such as cereals, legumes and potatoes. As such, these newly identified candidate genes could be used to construct more resistant crops and improve our food security in light of increased desertification of the planet.

The results came in the journal Proceedings of the National Academy of Sciences.

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