A 'footprint' of desiccation tolerance in the genome of Xerophyta viscosa

Desiccation tolerance is common in seeds and various other organisms but only a few Angiosperm species possess vegetative desiccation tolerance. These 'resurrection species' may serve as ideal models for the ultimate design of crops with enhanced drought tolerance. To understand the molecular and genetic mechanisms enabling vegetative desiccation tolerance we produced a high-quality whole-genome sequence for the resurrection plant Xerophyta viscosa and assessed transcriptome changes during its dehydration. Data revealed induction of transcripts typically associated with desiccation tolerance in seeds, and involvement of orthologues of ABI3 and ABI5, both key regulators of seed maturation. Dehydration resulted in both increased, but predominantly reduced transcript abundance of genomic 'clusters of desiccation-associated genes' (CoDAGs), reflecting the cessation of growth that allows for the expression of desiccation tolerance. Vegetative desiccation tolerance in X. viscosa was found to be uncoupled from drought-induced senescence. We provide strong support for the hypothesis that vegetative desiccation tolerance arose by redirection of genetic information from desiccation tolerant seeds.