show Abstracthide AbstractUnderstanding biological processes that underlie plant resilience to extreme abiotic conditions is a major challenge for plant biologists. This knowledge is essential to develop biotechnologies that could be used to improve crops in an era of climate change or to expand the limits of agriculture to marginal lands. Here we characterized three pristine and extreme ecosystems from Atacama Desert in Northern Chile. 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 mechanisms that allow these communities and plant species to inhabit these extreme environments.We sequenced the transcriptome of 32 most abundant and ecologically important species to explore gene functions. Our studies provide new insights into mechanisms for evolution of plant abiotic stress tolerance, and improve our understanding of the highly unique ecosystem of the Atacama Desert.