Adaptations to Stress Tolerance Archived in the Extremophile Genome of Thellungiella parvula

Thellungiella parvula, a close relative of Arabidopsis thaliana thrives in highly saline, degraded, and toxic soils. It is also drought and cold tolerant as adaptations that mark its lifestyle in the dry and extreme weathers of salt flats in Central Anatolia, Turkey. We recently sequenced the genome of T. parvula, the first genome assembly reported for an extremophile higher plant. T. parvula has a compact genome 15% larger than Arabidopsis with a relatively low repeat content of 7%. Arabidopsis and Thellungiella ancestors separated ~12 million years ago. Therefore, Arabidopsis and T. parvula have comparable co-linear gene spaces. Yet, there are significant differences in coding regions, regulatory elements, and genome restructuring. Copy number variation in T. parvula is highly pronounced in functional categories of transporters, signal transduction, and response to abiotic stresses compared to Arabidopsis. Even with co-linear single genes known to play important roles in stress adaptation, T. parvula has non-linear regulatory regions different from Arabidopsis. We will highlight the adaptation history engraved in the genome of a species with a niche carved out by multiple stresses.