Exploring Genetic Diversity of the Atacama Desert Flora Using High-Throughput Transcriptome Sequencing

The Atacama Desert is one of the driest places on Earth. Plants growing here are exposed to extreme environmental conditions like extremely low water availability, high diurnal 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 this study, our aim was to characterize the genetic diversity of plants growing on the western slopes of the Andes in the Atacama, and reveal the genetic bases of their extreme abiotic stress tolerance. To achieve these goals, we have chosen a transcriptomic approach. Until now, high-throughput transcriptome sequencing has been performed for 14 plant species representing different environmental conditions, using the Illumina platform. Sequencing reads were de novo assembled using Trinity software, and annotated by comparison against publicly available databases. In order to examine the most representative biological processes for each plant, we performed a Gene Ontology enrichment analysis. Beside genes associated to fundamental biochemical processes, we found a substantial overrepresentation of transcripts related to abiotic stress tolerance in several data sets. These genes are involved in responses to water deprivation, cold stress, heat stress, and oxidative stress. We have identified several novel stress-responsive genes, including dehydrin-like proteins, catalases, peroxidases, superoxide dismutases, heat shock proteins, and molecular chaperones. Our results provide new insights into plant abiotic stress tolerance, and improve our understanding of the highly unique ecosystem of the Atacama Desert.