Meta-analysis of the effects of abiotic factors on plant microbes

The abiotic environment exerts strong effects on plant-associated
microbes, shaping their interactions with plants and resulting ecosystem
processes. However, these abiotic effects on plant-microbe interactions
are often highly specific and contingent on the abiotic driver or
microbial group, requiring synthesis work describing general patterns and
from this generate hypotheses and guide mechanistic work. To address this,
we conducted a meta-analysis of the effects of climate change-related
abiotic factors, namely warming, drought, and eCO2, on plant-associated
microbes distinguishing by microbial taxonomic or biological group
(bacteria, fungi or virus) and the plant part where microbes are found or
associated with (phyllosphere or rhizosphere). We found abiotic
driver-specific patterns, whereby drought significantly reduced microbial
abundance, whereas warming and eCO2 had no significant effects. In
addition, these abiotic effects were contingent on the microbial taxonomic
group, with fungi being negatively affected by drought but positively
affected by warming (eCO2 enrichment had no effect), whereas bacteria and
viruses were not significantly affected by any factor. Likewise,
rhizopheric microbes were negatively affected by drought but positively
affected by warming (eCO2 enrichment had no effect), whereas phyllospheric
microbes were not significantly affected by any factor. Collectively,
these findings point to important implications for global change research
by highlighting contrasting effects of climate change-related abiotic
drivers on plant-associated microbes and the contingency of such effects
on microbe life histories and the nature of their interactions with
plants.