From intercropping to monocropping: The effects of Pseudomonas strain to facilitate nutrient efficiency in peanut and soil.

As an oilseed crop, the yield and quality of peanuts are severely constrained by nutrient deficiencies, particularly in calcareous soils in northern China. Maize-peanut intercropping is an effective strategy to enhance mineral nutrient efficiency in peanuts via plant-microbe interaction, but the underlying mechanisms remain elusive. Here, we conducted experiments using a Pseudomonas strain (Pse.IP6) with diverse beneficial characteristics, which was isolated from the rhizosphere of intercropped peanuts. Additionally, Pse.IP6 exhibits high phylogenetic similarity with the Amplicon Sequence Variants 48 (ASV48) which belongs to Pseudomonas and is positively correlated with Fe in plants and soil in intercropping. To confirm the plant growth-promoting potential of Pse.IP6 and its role in intercropping advantage, we constructed pot experiments. Results revealed that Pse.IP6 promoted shoot growth and root development, as well significantly enhanced SPAD value, net photosynthetic rate, stomatal conductance, and transpiration rate of peanut leaves. Moreover, the application of Pse.IP6 resulted in a notable accumulation of nitrogen (N), phosphorus (P), and potassium (K) in shoot and active iron (Fe) in leaves, accompanied by an increased K-N ratio. The primary reason for the nutrient promotion is the enhancement of the bioavailability of nitrate, ammonium, P, K, and Fe in the rhizosphere. Collectively, our findings demonstrate that Pse.IP6, enriched in intercropping peanut, is a plant growth-promoting bacteria, represented by transferring the intercropping advantage on nutrients activation to monocropping peanuts. Our results offer insights into plant-rhizobacteria interaction mechanisms and therefore provide a rhizobacteria-based pathway to improve nutrient efficiency and productivity of crops.