Researchers reveal ‘genetic gold mine’ underlying plant resilience in extreme desert environments

Researchers reveal

The Chilean research team established an unparalleled “natural laboratory” in the Atacama Desert in northern Chile, one of the driest and harshest environments on Earth. Credit: Melissa Aguilar

An international team of scientists has identified genes associated with plant survival in one of the harshest environments on Earth: the Atacama Desert in Chile. Their results, published in Proceedings of the National Academy of Sciences (PNAS), can help researchers breed resilient crops that can thrive in increasingly arid climates.

“In an era of accelerated climate change, it is crucial to uncover the genetic basis to improve crop production and resilience in dry and nutrient-poor conditions,” said Gloria Coruzzi, Carroll & Milton Petrie Professor at New York University (NYU) Department of Biology and Center for Genomics and Systems Biology, who co-led the study with Rodrigo Gutiérrez.

The study was an international collaboration between botanists, microbiologists, ecologists, evolutionary and genomic scientists. This unique combination of expertise enabled the team to identify the plants, associated microbes and genes that enable Atacama plants to adapt and flower under extreme desert conditions, which could ultimately help increase crop growth and reduce food insecurity. .

“Our study of plants in the Atacama Desert is directly relevant to regions around the world that are becoming increasingly dry, with factors such as drought, extreme temperatures and salt in water and soil posing a significant threat to global food production,” said Gutiérrez. , Professor at the Department of Molecular Genetics and Microbiology at the Pontificia Universidad Católica de Chile.

Establishment of a “natural laboratory” in one of the driest places on Earth

The Atacama Desert in northern Chile, sandwiched between the Pacific Ocean and the Andes Mountains, is the driest place on the planet (apart from the poles). Yet dozens of plants grow there, including grasses, annuals and perennial shrubs. In addition to limited water, plants in the Atacama must cope with high altitude, low availability of nutrients in the soil and extremely high radiation from sunlight.

The Chilean research team established an unsurpassed “natural laboratory” in the Atacama Desert over a 10-year period, collecting and characterizing the climate, soil and plants at 22 locations in different vegetation areas and heights (each 100 meters high). ) along the Talabre-Lejía Transect. By measuring a variety of factors, they recorded temperatures that fluctuated more than 50 degrees from day to night, very high radiation levels, soil that was largely sand and lacking nutrients, and minimal rainfall, with most annual rainfall falling over a few days.

Use of genomics to explore the development of resistant plants

The Chilean researchers brought the plant and soil samples – preserved in liquid nitrogen – 1,000 miles back to the laboratory to sequence the genes expressed in the 32 dominant plant species in Atacama and assess the plant-associated soil microbes based on DNA sequences. They found that some plant species developed growth-promoting bacteria near their roots, an adaptive strategy to optimize the uptake of nitrogen – a nutrient essential for plant growth – into the nitrogen-poor soil of the Atacama.

Researchers reveal

Gabriela Carrasco, a bachelor researcher at the time, identifies, labels, collects and freezes plant specimens in the Atacama Desert. These samples then traveled 1,000 miles, kept under dry ice to be processed for RNA extraction in Rodrigo Gutiérrez’s laboratory in Santiago de Chile. The species Carrasco collects here are Jarava frigida and Lupinus oreophilus. Credit: Melissa Aguilar

To identify the genes whose protein sequences were adapted in the Atacama species, the researchers at NYU then performed an analysis using an approach called phylogenomics, which aims to reconstruct evolutionary history using genomic data. In consultation with colleagues in the New York Botanical Gardens, they compared the genomes of the 32 Atacama plants with 32 non-adapted but genetically similar “sister” species, as well as several model 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 development of the Atacama plant’s adaptation to desert conditions,” Coruzzi said.

“This computationally intense genomic analysis involved comparing 1,686,950 protein sequences across more than 70 species. We used the resulting 8,599,764 amino acid supermatrix to phylogenomically reconstruct the evolutionary history of the Atacama species,” said Gil Eshel, who performed this analysis. using the High Performance Computing Cluster at NYU.

The study identified 265 candidate genes whose protein sequence changes were selected by evolutionary forces across several Atacama species. These adaptive mutations occurred in genes that could underlie plant adaptation to desert conditions, including genes involved in response to light and photosynthesis, which can enable plants to adapt to the extreme highlight radiation in Atacama. Similarly, the researchers revealed genes involved in the regulation of stress response, salt, detoxification, and metal ions that could be related to the adaptation of these Atacama plants to their stressful, nutrient-poor environment.

What we can learn from this “genetic gold mine”

Most of the scientific knowledge about plant stress responses and tolerance has been generated through traditional laboratory-based studies with a few model species. Although beneficial, such molecular studies are likely to miss the ecological context in which plants have evolved.

“By studying an ecosystem in its natural environment, we were able to identify adaptive genes and molecular processes among species facing a generally harsh environment,” said Viviana Araus of the Pontificia Universidad Católica de Chile in Gutierrez’s laboratory and a former postdoctoral fellow at NYU’s Center for Genomics and Systems Biology.

“Most of the plant species we characterized in this research have not been studied before. Since some Atacama plants are closely related to basic crops, including cereals, legumes and potatoes, the candidate genes we identified represent a genetic goldmine to develop. more resilient crops, a necessity given the increased desertification of our planet, “Gutiérrez said.

In addition to Gutiérrez and Araus, their partners in Chile included Claudio Latorre of the Pontificia Universidad Católica de Chile and Mauricio González of the Universidad de Chile. Coruzzi and Eshel at NYU worked on the phylogenomic pipeline and analysis with collaborators in the United States, including Kranthi Varala of Purdue University, Dennis Stevenson of the New York Botanical Garden, Rob DeSalle of the American Museum of Natural History, and members of their research team.


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More information:
Plant ecological genomics at the frontiers of life in the Atacama Desert, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073 / pnas.2101177118

Provided by New York University

Citation: Researchers Reveal ‘Genetic Gold Mine’ Underlying Plant Resilience in Extreme Desert Environment (2021, November 1) Retrieved November 1, 2021 from https://phys.org/news/2021-11-uncover-genetic-goldmine-underlying-resilience.html

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