P-529 - The liverwort microbiome mitigated drought stress in Arabidopsis thaliana and in Marchantia polymorpha

One of the most dramatic environmental transitions in the evolutionary history of plants is the shift from an aquatic to a terrestrial environment. Approximately 450 million years ago, green algae successfully established themselves on land, encountering various abiotic stresses such as desiccation, radiation, and pathogens. To adapt to the dry environment, multiple evolutionary events must have been selected, and symbiotic interactions have also been proposed as factors contributing to these innovations. Among these interactions, plant–bacteria interactions are expected to have contributed to overcoming abiotic stresses during terrestrialization.

Here, we hypothesized that microbiome of liverworts, an ancient land plant, has members of bacteria who can help plants to thrive on dry land. The rhizosphere microbiome of liverworts was analyzed and three strains out of seven rhizosphere-enriched strains were selected. With these three strains, we conducted simple drought stress test using a model plant Arabidopsis thaliana and a liverwort Marchantia polymorpha. It is revealed that two strains Brevundimonas lenta and Caulobacter rhizosphaerae could mitigate regeneration after dehydration in Arabidopsis. And B. lenta and Sphingomonas algorifonticola enhanced chlorophyll contents in M. polymorpha under drought stress. Also, these bacterial strains seem to prime the expression of drought stress-responsive genes in Arabidopsis under drought conditions. These findings suggest that bacterial microbiome of liverwort might contribute to alleviating plant drought stress.