Dryness decouples interactions between soil and root-associated microbiota in grassland

Abstract:

Microorganisms play key roles in the functioning of terrestrial ecosystems, however, knowledge about root-associated microbiome communities and how their interactions shift across environmental gradients is lacking. Here, we present results from a study conducted across 84 grassland sites to assess the effect of environmental factors on the diversity, composition, function and co-occurrence networks along the soil-root continuum (soil, rhizosphere, rhizoplane and endosphere) using bacterial 16S DNA amplicon sequencing. Our results showed that the rhizo-compartments and grassland types were the two major sources of variation of the bacterial community structure and function at a regional scale. Both abiotic and biotic factors had significant effects on soil and root microbiota, and MAP and aridity played the most important roles in influencing the soil and root microbiome. More importantly, our results indicated that the inner networks of the soil and rhizo-compartment community destabilized in the low precipitation area, whereas the endosphere networks became stable, and dryness decoupled the relationships among the microbiota between the rhizo-compartment and soil but strengthened the linkage between the rhizo-compartment and endosphere. Moreover, the study also inferred that dryness altered the function related to the C and N cycles of the soil and root-associated microbes and strongly increased the abundance of denitrification genes in the desert grassland. Our findings provide new insight into the acclimation regulation strategy in response to the environment by regulating the cooperation of soil and root microbiota communities.