Transcriptional regulation of the response to water availability in the resurrection plant Xerophyta elegans
Vegetative desiccation tolerance (VDT) has evolved independently across vascular plants, but its genetic basis remains poorly understood. Although VDT is associated with expansion of the ELIP gene family, the contribution of other lineage-specific expansions is unclear. We assembled genomes for Xerophyta elegans and Xerophyta humilis, identifying expanded gene families largely involved in chlorophyll metabolism and abscisic acid-mediated stress responses. Using a dense dehydration-rehydration transcriptome series in X. elegans seedlings, we reconstructed the regulatory network underlying VDT. Transcription factors from the ABF, ZAT and HSFC families were associated with early responses to desiccation. Key regulators of the seed maturation programme, including NAC transcription factors (ATAF1 and ANAC032), DOG genes and the trihelix factor ASIL1, were also implicated. These findings indicate that VDT arises through integration of abiotic stress signalling with rewiring of the seed maturation network, enabling desiccation tolerance in vegetative tissues.