Rhizosphere soil architecture determined rhizospheric microbiome
acquisition
Our results demonstrate that soil physical architecture surrounding the
root zone was associated with the recruitment of rhizosphere microbiome
from bulk soil, but only at the basal zone of the root system, possibly
because the apical root has such a short soil-residence period (1 day vs
15 days of basal root) to change rhizosphere porosity. In addition,
basal roots may accumulate more root exudates in the rhizosphere than at
the root tip, which may modulate rhizosphere porosity (Rabbi et al.,
2021). In the rhizosphere of basal root, increased soil porosity was
correlated with enriched Actinobacteria, Acidobacteria, and Chloroflexi
microbes, but reduced Firmicutes microbes and one core ASV, annotated as
unclassified Micrococcaceae (Fig. 6 ). Modification of soil
porosity by root elongation can alter microhabitats, through changes in
gas and water flow (Young and Bengough, 2018). In chickpea plants, a
more porous architecture of rhizosphere soil can favour water and gas
permeability (Rabbi et al., 2018; Rabbi et al., 2021). Firmicute
bacteria might prefer the rhizosphere microsite with smaller pore volume
and less oxygen, as Firmicutes included the Clostridia class, which is a
group of anaerobic bacteria (Teixeira et al., 2010). The enrichment and
isolation under anaerobic conditions also confirmed a higher diversity
of Firmicute isolates (Malele et al., 2018).