Maize root microbiomes along a soil texture gradient

Soil texture is critical to root growth and an important determinant of the occurrence and distribution of soil microbiota. It is still an open question how soil texture and its influence on root growth feeds back on root microbiome assembly. We manipulated soil texture by increasing the loam proportion and thereby achieved a gradient of decreasing bulk density. We grew maize (Zea mays L.) in these soils, measured changes in root traits and sampled bulk soil and rhizosphere to apply amplicon based high-throughput sequencing. We investigated changes in root morphology of maize and the concomitant shift in prokaryote (archaea and bacteria) and protist (Cercozoa and Endomyxa) diversity, community composition and co-occurrence in the maize rhizosphere along the soil texture gradient. A linear relationship between bulk density and root morphology and a shift in microbial diversity along the soil texture gradient, as well as a stronger selection effect of the rhizosphere in soils with a high sand fraction (and high bulk density) were found.