The belowground of the resurrection plant Myrothamnus flabellifolia: Exploring the desiccation-tolerant root-associated microbiome

Aims and Background The resurrection plant Myrothamnus flabellifolia tolerates complete desiccation and is a great model for studying how plants cope with extreme drought. The response to desiccation in M. flabellifolia leaves has been studied extensively, but little is known about how the associated microbiome contributes to desiccation tolerance. Root-associated microbes play a major role in stress tolerance, and are an attractive target for enhancing drought tolerance in staple crops. However, how these dynamics play out under the most extreme water limitation remains underexplored. Methods The high-throughput amplicon metagenomic technique was used to investigated the bacterial and fungal communities in the bulk soil, rhizosphere, and endosphere of the M. flabellifolia. Results The bacterial phyla that were most abundant across all compartments were Acidobacteriota, Actinobacteria, Chloroflexi, Planctomycetes andProteobacteria, while fungal phyla were Ascomycotaand Basidiomycota. Although the bulk soil hosted multiple beneficial root-associated microbes, the rhizosphere compartment showed the highest functional diversity of bacteria and fungi. In contrast, the endosphere exhibited a low abundance and diversity of microbes. These findings suggest that M. flabellifolia recruits soil microbes from bulk to rhizosphere, many of which may confer extreme drought tolerance and promote plant growth. Conclusion The diverse rhizosphere microbiome is filtered to result in a highly selective endosphere microbiome. We find that compartment niches act as the major driver of microbial diversity, but that soil physicochemical factors also influence the microbial composition. These results suggest that the root-associated microbiome of M. flabellifolia is highly structured and may aid in plant function.