In vitro Assessment of Pseudomonas sp. Strain FCBB-2 for Effective Plant Growth Promotion and Antifungal Activity under Drought Stress

The significance of plant growth-promoting rhizobacteria (PGPR) in plant adaptation to harsh conditions is still unknown. Native bacteria were isolated from rhizospheric soils and tested for growth-promoting qualities as well as antagonistic capabilities against phytopathogenic fungi in this investigation. All the Pseudomonas spp. strains were characterized for in vitro drought tolerance in trypticase soy broth supplemented with different concentrations of polyethylene glycol (PEG6000). Out of nine isolates, only one strain was able to tolerate maximum level of stress (−1.03 MPa) and is further screened for plant growth promoting (PGP) properties under non-stress and drought stress conditions. Strain FCBB-2 isolated from cluster bean plant rhizosphere soil, showed multiple PGP activities such as indole-3-acetic acid (IAA) production, siderophore, hydrogen cyanide (HCN) production and exopolysaccharide (EPS) production and antifungal activity under non-stress and drought stress conditions against various plant fungal pathogens like Fusarium oxysporum, Macrophomina phaseolina, Alternaria alternata, Sclerotium hydrophilium, Pythium aphanidermatum and Rhizoctonia solani. The strain FCBB-2 was identified as Pseudomonas aeruginosa based on morphological and 16S rRNA gene sequence analysis and the sequence was submitted to NCBI GenBank under the accession number KT311003.