Wild plant species with broader precipitation niches exhibit stronger host selection in rhizosphere microbiome assembly

Plants actively recruit microbes from the soil, forming species-specific root microbiomes. However, their relationship with plant adaptations to temperature and precipitation remains unclear. Here we examined the host-selected and conserved microbiomes of 13 native plant species in the Xinlingol steppe, Inner Mongolia, a semi-arid region in China. Through calculating plant global precipitation and temperature niches, plant phylogenetic distances and functional traits, we found that these factors significantly influenced rhizosphere microbiome assembly. We further quantified the strength of host selection and observed that plants with wider precipitation niches exhibited greater host selection strength in their rhizosphere microbiome assembly and higher rhizosphere bacterial diversity. In general, the rhizosphere microbiome showed a stronger link to plant precipitation niches than temperature niches. Haliangium exhibited consistent responsiveness to host characteristics. Our findings offer novel insights into host selection effects and ecological determinants of wild plant rhizosphere microbiome assembly, with implications for steering the root microbiomes of wild plants and understanding plant-microbiome evolution.