Work

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

Year: 2026

Type: preprint

Abstract: Pyrroloquinoline quinone (PQQ) is known to promote plant growth, yet how the rhizosphere microbiome varies with PQQ concentration remains poorly understood. We applied metagenomic sequencing to characterize the taxonomic composition and functional potential of the tobacco rhizosphere microbiome across PQQ treatments at 0.5, 1 and 2 μmol/L plus an untreated control. The rhizosphere microbiome was dominated by Pseudomonadota and Actinomycetota and differed among treatments in a concentration-associated, non-monotonic manner. The most pronounced differences were observed at 1 μmol/L, where alpha diversity showed dimension-specific variation and beta-diversity analysis resolved the most distinct community profile. Taxonomic and functional profiles varied concurrently, with Streptomyces , Sphingomonas , Rhodanobacter and Lysobacter , together with functions related to biosynthesis, energy metabolism, colonization and environmental sensing, showing higher relative abundance at this concentration. No broad-spectrum antimicrobial effect was detected at the community level, and antibiotic resistance gene abundance showed no significant differences among treatments after correction for multiple testing. These findings provide a basis for further evaluation of PQQ in modulating the rhizosphere microbiome in continuous cropping systems. Statement of significance For the first time in tobacco, we demonstrate that PQQ governs the rhizosphere microbiome in a concentration-associated yet non-monotonic manner, resolving the most distinctive community architecture at 1 μmol/L, where Pseudomonadota and Actinomycetota predominate and alpha diversity shifts dimension-specifically. Notably, taxonomic and functional trajectories co-vary, driving concurrent enrichment of Streptomyces , Sphingomonas , Rhodanobacter and Lysobacter together with functions underpinning biosynthesis, energy metabolism, colonization and environmental sensing. Crucially, the absence of broad-spectrum antimicrobial activity and of significant antibiotic resistance gene changes positions PQQ as a novel, microbiome-targeted candidate, supporting its further evaluation in modulating rhizosphere microbiomes in continuous cropping systems.

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.64898/2026.10.08.757804