Potassium-Solubilizing Bacteria Mediate Light-Potassium Synergy to Enable Native Pueraria lobata to Outcompete...

The invasive vine Mikania micrantha H. B. K. poses severe threats to biodiversity and ecosystem stability in tropical and subtropical regions, calling for sustainable ecological approaches. This study explores how the native legume Pueraria lobata var. thomsonii Benth displaces M. micrantha in the field, with a focus on the synergistic roles of light capture advantage and rhizosphere potassium (K) dynamics driven by specialized bacteria. In competitive ecotones, P. lobata demonstrated superior growth and photosynthetic performance relative to M. micrantha. Its main stem length was 1.31 times greater, while net photosynthetic rate, stomatal conductance, and chlorophyll content were 80%, 110.7%, and 21.4% higher, respectively. Soils associated with P. lobata contained significantly higher available K, correlated with enhanced enzyme activities, indicating a "microbe-enzyme-K" activation cascade. P. lobata specifically enriched efficient potassium‑solubilizing bacteria (KSB), such as Pseudomonas and Acinetobacter. Isolated KSB strains exhibited K‑solubilizing and plant‑growth‑promoting capacities and increased the competitive balance index of P. lobata in inoculation assays. Partial least‑squares discriminant analysis confirmed that KSB‑mediated K mobilization boosted stem elongation primarily by improving photosynthetic potassium use efficiency (PKUE), forming a reinforcing "light-K-microbe" loop that drives competitive displacement. This work establishes a "microbe‑mediated invasion suppression" framework, demonstrating how a native plant can couple superior light‑use efficiency with a specialized rhizosphere microbiome to outcompete an invasive species. We propose that managing potassium‑solubilizing microbiomes offers a sustainable strategy for ecological restoration in K‑limited ecosystems.