Phosphorus solubilizing Bacillus altitudinis WR10 alleviates wheat phosphorus deficiency via remodeling root system architecture, enhancing phosphorus availability, and activating the ASA-GSH cycle.

Background and Aims: Phosphorus (P) deficiency is present in 70% of the world's arable land, and severely affects crop growth and productivity. In this study, the ameliorative effects of P-solubilizing Bacillus altitudinis WR10 on P deficiency in wheat were investigated and the underlying mechanisms were explored. Methods: Wheat was grown in half-strength Hoagland solution with KH2PO4 or Ca3(PO4)2 with or without WR10 inoculation for 14 days. Wheat biomass, root system architecture (RSA), and tissue P content were determined to evaluate the potential for alleviating P deficiency. To elucidate the underlying mechanisms, the ability of WR10 to produce organic acids (OAs), and its effects on root exudates and the ascorbic acid-glutathione (ASA-GSH) cycle in wheat were investigated. Results: WR10 significantly increased plant biomass and tissue P content, decreased the root/shoot ratio, and remodeled the RSA, predominantly by augmenting root diameter in P-deficient wheat. Under P deficiency, WR10 produced up to 72 OAs, including palmitic, fumaric, methylmalonic, elaidic, benzoic, and nonanoic acids, decreased pH of the culture solution, and increased soluble P content. Our split-root experiment and non-targeted metabolomics revealed that WR10 inoculation reprogrammed root exudated in P-deficient plants, which enhanced the contents of (−)-threo-isodihomocitric, (R)-2-ethylmalic, 4Z,7Z,10Z,13Z-hexadecatetraenoic, and colnelenic acids. In addition, WR10 significantly upregulated APX, MDHAR, DHAR, GR, and GS gene expression levels and increased the ASA and GSH contents involved in the ASA-GSH cycle, thereby decreasing H2O2 levels. Conclusion: B. altitudinis WR10 alleviates P deficiency in wheat by remodeling the RSA, improving P availability, and activating the ASA-GSH cycle. [ABSTRACT FROM AUTHOR]