Transcriptomic Analysis of Plants Growing on the Western Slopes of the Andes in the Atacama Desert

The Atacama Desert is one of the driest places on Earth. Plants grown here are exposed to challenging environmental conditions like extremely low water availability, large temperature oscillations, nutrient-poor soils with high salt content, and high levels of solar radiation. Despite these harsh conditions, the Atacama hosts a surprising diversity of plant life. It is poorly understood how plants can adapt to this highly demanding environment. In the central Atacama Desert, the western slopes of the Andes provide a natural altitudinal gradient of environmental parameters, such as rainfall and temperature. As a consequence, various plant communities succeed each other at different elevations: the pre-puna (2400 – 3300 m a.s.l), the puna (3300 – 4000 m a.s.l.), and the high Andean steppe (4000 – 4500 m a.s.l.). Yet, very little is known about the underlying genetic diversity of plant species inhabiting these native communities. In this study, our aim was to characterize the genetic diversity of six plant species growing on the western slopes of the Andes in the Atacama, and identify candidate genes that could underlie their extreme abiotic stress tolerance. To achieve these goals, we have chosen a transcriptomic approach. Three species belong to Asterales, this order is represented by the highest number of species at our study site. Ambrosia artemisioides was collected from the pre-puna zone, Chuquiraga atacamensis is from the puna, and Senecio puchii is from the steppe. Lupinus subinflatus and Adesmia erinacea are representatives of Fabales, they might have an important role in the nitrogen-deficient desert environment through their association with nitrogen-fixing bacteria. A desert annual, Exodeconus integrifolius, from the Solanales order, was collected in the pre-puna, and found growing even at the edge of the absolute desert. Our studies provide new insights into plant abiotic stress tolerance, and improve our understanding of the highly unique ecosystem of the Atacama Desert.