Metagenomic insights into dose-dependent alterations in the tobacco rhizosphere microbiome by pyrroloquinoline quinone

Pyrroloquinoline quinone (PQQ) is known to enhance plant growth, but the impact on the tobacco rhizosphere microbiome at different concentrations is not well understood. Researchers applied metagenomic sequencing to examine the microbial composition and functionality of the tobacco rhizosphere at three PQQ concentrations – 0.5, 1, and 2 mol/L – in addition to an untreated control.

The microbiome was predominantly composed of Pseudomonadota and Actinomycetota, and its composition varied non-monotonically with PQQ concentration. The most significant differences in the microbiome were observed at 1 mol/L, where alpha diversity displayed varying patterns across dimensions and beta-diversity analysis revealed the most distinct community profile.

At this concentration, the relative abundance of Streptomyces, Sphingomonas, Rhodanobacter, and Lysobacter increased, alongside functions associated with biosynthesis, energy metabolism, colonization, and environmental sensing. No broad-spectrum antimicrobial effect was detected at the community level, and antibiotic resistance gene abundance did not differ significantly among treatments after accounting for multiple testing.

These findings suggest that PQQ can modulate the rhizosphere microbiome in a concentration-dependent manner, offering a foundation for further investigation of PQQ's role in continuous cropping systems.