3.5 Correlation network
Correlation network analysis indicated that positive correlation
occurred within prokaryotic or eukaryotic groups in microbiota of aerial
parts and roots. In aerial tissues, positive correlation was observed
among endophytic bacterial genera, while negative correlation occurred
among fungal genera (Fig. 4a). For example, unidentified fungal OTU_673
and OTU_702 showed strong negative correlations to several fungal taxa.
Meanwhile, positive correlation could be also observed between
prokaryotic or eukaryotic members. In roots, bacterial or fungal members
in the community were more connected (Fig. 4b). Concatenated negative
correlations were observed between prokaryotic and eukaryotic members,
which suggested intensive antagonism between bacteria and fungi in
roots. These findings indicate denser inter-kingdom interactions in the
roots rather than in the aerial tissues.
Network analysis of endophytic bacterial communities suggested a minor
effect of radiation on the topology of endophytic bacterial network. The
network of endophytic bacterial communities in aerial tissues showed
similar connectance and modularity across control and three radioactive
treatments (Table 1). Meanwhile, the root bacterial communities showed
higher connectance in control and similar modularity in control and
radioactive environments. Simultaneously, radiation showed a strong
effect on the topology of endophytic fungal correlation network. Higher
modularity and lower connectance were observed in all radiation levels
compared to control regardless of the tissue type (aerial tissues or
roots) (Table 1).