Deciphering the genome of the endophytic bacterium Pseudomonas retamae type strain RB5T: A prominent plant growth promoter for wheat with potential applications in sustainable agriculture

This study focused on unraveling the plant growth-promoting properties of Pseudomonas retamae type strain RB5T, a newly described species isolated from root nodules of Retama monosperma, a drought-tolerant coastal legume, and evaluating its effects on wheat growth and resilience. P. retamae RB5T exhibited several PGP traits, including the production of indole acetic acid (IAA, 18 ± 3.48 μg/mL) and phosphate solubilization activity (8.14 ± 0.25 cm). It also tolerated salinity up to 6 %, thrived at 42 °C, and displayed antagonistic activity against Fusarium oxysporum. Notably, the strain significantly enhanced shoot and root biomass of wheat seedlings in vitro, under greenhouse conditions, and in field trials. To gain insight into the genetic basis of these traits and to better understand the endophytic nature of the strain, we conducted in silico analysis of the complete genome. Genome annotation revealed gene clusters related to auxin biosynthesis (iaaH, iaaM), nitrogen metabolism (glnGKL, cyn, nas, nor), phosphate solubilization (phnCDEP, phoABHLU, pstABCHS), and antimicrobial compound production (phzF, fusABCDE). Genes involved in abiotic stress tolerance, such as katE, superoxide dismutases, hsp, capA, betT, and heavy metal resistance, were also identified. These findings confirm the potential of P. retamae RB5T as an eco-friendly bioresource primed for fostering plant growth, particularly in drought-prone regions.