Unveiling the genetic basis of biochemical pathways of plant growth promotion in and the first genomic insights into as a biostimulant.

species are among the most promising plant growth-promoting bacteria (PGPB) due to their adaptability to various environmental niches and extensive biosynthetic capabilities. Despite the available data on the PGP-traits (PGPTs) of , the genetic basis underlying their beneficial effects remains largely unexplored. In this study, a comparative genomic analysis of three and one strains, isolated from the maize rhizosphere, is presented to elucidate the molecular mechanisms behind their PGP-traits. All strains exhibited multiple PGP-traits, including phosphate solubilization, phytohormone and siderophore production, growth in nitrogen-free medium, stress tolerance, and biofilm formation. Phylogenomic analysis revealed that plant-associated strains have higher genetic similarity, emphasizing niche-specific evolution. Genome analyses revealed strain- and species-specific adaptations, particularly in relation to nutrient acquisition and abiotic stress response mechanisms. strains encoded alternative sigma factors (SigB, SigM, SigW) enabling enhanced salt tolerance, whereas lacked this system and relied on conventional osmoprotective strategies. The strains utilized different tryptophan-dependent (IAN, IAM or IPyA) pathways for auxin biosynthesis and differed in phosphate solubilization ability, which can be attributed to upstream and missense variants in genes affecting acid metabolism (, and and phosphatase () activity. Iron uptake bacillibactin-siderophores was exclusive to . The inability of the strain to acquire iron was associated with structural variants (absence of gene) within the bacillibactin biosynthetic gene cluster. This work provides new insights into the molecular basis of PGP traits in and supports the development of -based bioinoculants for sustainable agriculture.