Engineered Bacillus subtilis p43-Taglo1 enhances arsenic resistance and root colonization under As(III) stress. Through increased extracellular polymeric substance production, Fe(II) oxidation, and siderophore secretion, the strain promotes formation of an iron plaque-biofilm composite on rice roots. This root-surface barrier sequesters arsenic, reduces arsenic uptake, and supports rice growth in contaminated paddy systems. Lijuan Li et al 2026 - New Phytologist
Summary
- Arsenic contamination threatens rice (Oryza sativa) production, yet the synergistic use of iron plaque (IP) and root-associated biofilms as a rhizosphere barrier to limit arsenic uptake remains unexplored.
- To address this, we engineered an arsenic-resistant (AR) plant growth-promoting rhizobacterium (AR-PGPR), Bacillus subtilis p43-Taglo1, expressing the speciation-inert arsenic-binding protein TaGlo1. In a contaminated paddy, this strain increased grain yield by 10.7–11.6% and reduced grain arsenic by 28.2–37.4% compared to the wild-type.
- The engineered strain robustly colonized roots and enhanced the formation of a functional IP-biofilm composite, which sequestered more arsenic. This was driven by a 2.87-fold increase in Fe(II) oxidation and elevated production of extracellular polymeric substances (EPS) (1.4-fold) and siderophores (1.5-fold). Transcriptomic analysis revealed that inoculation upregulated bacterial genes for Fe(II) oxidation, siderophore, and EPS biosynthesis, while in rice roots, it activated phytohormone pathways and downregulated arsenite transporters (OsLsi1 and OsLsi2).
- We conclude that AR-PGPR can restore beneficial root–microbe interactions under arsenic stress. The IP-biofilm composite acts as an inducible barrier essential for the dual benefits of arsenic exclusion and growth promotion. Our study shows that AR rhizobacteria fortify the IP-biofilm composite to reduce arsenic uptake and promote rice growth, providing a route toward safer rice production in arsenic-affected regions.
First published: 13 May 2026
Li, L., Zhang, N., Wang, T., Zhao, F.-J., Zhang, T., Huo, L., Wei, Y., Zeng, X. and Su, S. (2026), Engineered Bacillus subtilis p43-Taglo1 fortifies the iron plaque-biofilm composite to reduce arsenic uptake and promote rice growth. Full paper : New Phytol. https://doi.org/10.1111/nph.71255