Rhizosphere reprogramming by phosphate slag enhances glutathione-centered redox regulation and root development in tobacco

ABSTRACT:

Background and aims: Phosphate slag, a by-product of phosphorus and steel production, is a potential soil amendment that improves nutrient availability and redox stability. However, how it reshapes the rhizosphere microbiome and metabolism to promote tobacco (Nicotiana tabacum L.) root development remains unclear. This study aimed to elucidate the mechanisms by which phosphate slag reprograms rhizosphere microbial and metabolic networks, focusing on glutathione-centered redox regulation and carbon flux balance.

Methods: Metagenomic sequencing and untargeted metabolomics were integrated with soil and plant trait analyses in two tobacco-growing regions of Yunnan, China-Jiuxiang and Gengjiaying. Three treatments were tested: control (C), phosphate slag (P), and phosphate slag plus microbial conditioner (PM).

Results: Phosphate slag markedly reprogrammed the rhizosphere microbiome and metabolome, enriching taxa and pathways related to glutathione and ascorbate-aldarate metabolism, which enhanced antioxidant buffering and redox balance. Activation of the pentose phosphate pathway (PPP) supplied NADPH for glutathione recycling but reduced TCA flux and ATP synthesis, producing thicker but shorter roots. Increased siderophore and amino acid metabolism indicated improved nutrient mobilization. Multi-omics integration revealed coordinated microbe–metabolite interactions-microbes linked to potassium traits (TP, K₂O) and metabolites to sugar and alkaloid pools (TS, RS, TPA). Validation in Gengjiaying confirmed the reproducibility of these responses.

Conclusion: Phosphate slag enhances tobacco root growth by strengthening glutathione-mediated redox regulation and nutrient cycling. Yet, excessive PPP activation or microbial competition may limit energy supply. Balancing carbon and nutrient fluxes could optimize slag’s agronomic benefits and promote sustainable soil management.

INSTRUMENT(S): Liquid Chromatography MS - negative - reverse phase, Liquid Chromatography MS - positive - reverse phase

PROVIDER: MTBLS13273 | MetaboLights | 2026-01-16

REPOSITORIES: MetaboLights