Synergistic application of Funneliformis mosseae and selenite drives rhizosphere microbiota remodelling and selenium biofortification in rice seedlings.

Abstract

Rice is a critical dietary selenium (Se) source, but its Se biofortification potential is constrained by low soil Se availability in typical agroecosystems. While microbial interventions and Se fertilization are recognized as effective strategies, their integrated effects on Se translocation dynamics from early growth stages to mature grains remain understudied. This study investigates the synergistic potential of Funneliformis mosseae and selenite application during the seedling stage to enhance Se accumulation efficiency and grain biofortification. A pot experiment using typical paddy soil evaluated four treatments: control (CK_Se0), F. mosseae alone (F_Se0), selenite alone (CK_Se0.5), and combined F. mosseae and selenite (F_Se0.5). Plant biomass, Se concentrations in tissues/grains, rhizosphere microbial communities (16S/ITS sequencing) and soil Se fractions were analysed. F_Se0.5 increased shoot/root dry weights by 104.5%/79.4% (P < 0.05) compared to CK_Se0, with 2.5-fold (shoots) and 6.4-fold (roots) Se enrichment. Meanwhile, the content of available selenium in soil (SOL-Se + EX-Se) increased by 78.9% (P < 0.05). Microbiomic analysis showed F_Se0.5 reshaped soil microbial communities, enriching Se-redox functional taxa (e.g. Massilia, Fusicolla). This accelerated the transformation process of bioavailable selenium fractions in the soil, thereby promoting efficient selenium accumulation in mature grains. Additionally, inoculation with F. mosseae played a dominant role in driving changes in the rhizosphere microbial community, with the fungal community shifting from a stochastic to a deterministic process. This study identifies seedling-stage F. mosseae-Selenite synergy as a critical strategy for optimizing Se biofortification. By coordinating microbial community restructuring with plant Se uptake dynamics, our findings provide a sustainable framework for enhancing agricultural Se utilization efficiency.