Ultra deep sequencing of the prokaryotic community in the rhizosphere of field grown barley reveals negative effects of elevated CO2 concentrations on rare microbial taxa

Ultra-deep sequencing of PCR-amplified V4-region of the 16S rRNA genes from directly extracted DNA was applied to study the response of the rhizosphere prokaryotic community of winter barley grown under field conditions and exposed to elevated CO2 (eCO2) during the growing season. Six replicate samples grown under ambient (aCO2) and eCO2 conditions were sampled at anthesis. Based on a total of almost one million quality filtered DNA sequences, the results demonstrate that the overall prokaryotic community composition was not changed by eCO2, whereas the relative abundance and richness of single taxa were, in most but not all cases, negatively affected by eCO2.