Crop Type Exerts Greater Influence Upon Rhizosphere Phosphohydrolase Gene Abundance and Phylogenetic Diversity than Phosphorus Fertilization.

Rock phosphate is considered as an alternative form of phosphorus fertilizer in acidic, nutrient depleted soils of the Brazilian Cerrado. However, there is no information regarding the influence of phosphorus fertilizer sources in Cerrado soils upon microbial genes coding for phosphohydrolase enzymes in crop rhizospheres. Here, we analyse a field experiment comparing phosphorus fertilization (rock phosphate and triple superphosphate) of maize and sorghum upon crop performance, phosphatase activity and rhizosphere microbiomes at three levels of diversity: small subunit rRNA marker genes of bacteria, archaea and fungi; a suite of alkaline and acid phosphatase and phytase genes; and ecotypes of individual genes. We showed that there is no significant difference in crop performance between the fertilizers sources. Differences in rhizosphere microbiomes were observed at all levels of biodiversity due to crop type, but not fertilization. Inspection of phosphohydrolase gene ecotypes responsible for differences between the crops suggests a role for lateral genetic transfer in establishing ecotype distributions. Our results suggest development of inocula of microorganisms harbouring the gene ecotypes identified in this study, or selective breeding of crops with an enhanced capacity to attract beneficial microorganisms to the rhizosphere may prove useful to optimizing rock phosphate fertilizer in Cerrado soils.