Abstract
The effect of elevated atmospheric CO 2 concentration [CO 2] on the diversity and composition of the prokaryotic community inhabiting the rhizosphere of winter barley (Hordeum vulgare L.) was investigated in a field experiment, using open‐top chambers. Rhizosphere samples were collected at anthesis (flowering stage) from six chambers with ambient [CO 2] (approximately 400 ppm) and six chambers with elevated [CO 2] (700 ppm). The V4 region of the 16S rRNA gene was PCR‐amplified from the extracted DNA and sequenced on an Illumina MiSeq instrument. Above‐ground plant biomass was not affected by elevated [CO 2] at anthesis, but plants exposed to elevated [CO 2] had significantly higher grain yield. The composition of the rhizosphere prokaryotic communities was very similar under ambient and elevated [CO 2]. The dominant taxa were Bacteroidetes, Actinobacteria, Alpha‐, Gamma‐, and Betaproteobacteria. Elevated [CO 2] resulted in lower prokaryotic diversity in the rhizosphere, but did not cause a significant difference in community structure.
Highlights
Rising atmospheric CO2 concentration is an important component of climate change
The atmospheric CO2 concentration was elevated to approximately 700 ppm during daylight hours in six open-top chambers (OTCs), while in another six OTCs, the plants were exposed to the ambient, approximately 400 ppm, atmospheric [CO2]
We found that the rhizosphere prokaryotic community of barley was dominated by Proteobacteria, Bacteroidetes, and Actinobacteria
Summary
Rising atmospheric CO2 concentration is an important component of climate change. The globally averaged abundance of atmospheric CO2 has increased from 278 ppm in 1750–390.5 ppm in 2011 and is predicted to reach 700 ppm by the end of this century (IPCC, 2013). Recent studies investigating the effect of elevated [CO2] on the soil or root- associated prokaryotic diversity or community composition reported contradictory results showing either significant (Deng et al, 2012; He et al, 2012; Gschwendtner et al, 2015; Okubo et al, 2015) or no effects (Butterly et al, 2016; Hayden et al, 2012; Ren et al, 2015). Despite its agricultural significance and applicability as a model for other cereal crops, there is little information available if climate change might alter the interaction of barley with the soil microbiota This is true with respect to the response of the rhizosphere prokaryotic community of barley to increasing atmospheric [CO2]. We used Illumina MiSeq sequencing of 16S rRNA gene amplicons to obtain a magnitude higher resolution of the prokaryotic community composition than previous studies
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