Plant growth-promoting potential of endophytic bacteria isolated from roots of wild Dodonaea viscosa L.

Dodonaea viscosa, a wild and perennial shrub that can tolerate harsh environmental conditions, was used for the isolation of its endophytic bacteria and their potential was explored for the promotion of Canola growth. The bacteria identified through 16S rRNA gene sequencing, belonged to ten different genera namely Inquilinus, Xanthomonas, Pseudomonas, Rhizobium, Brevundimonas, Microbacterium, Bacillus, Streptomyces, Agrococcus and Stenotrophomonas. All the strains produced small amount of IAA (indole acetic acid) in the absence of tryptophan and comparatively more in the presence of tryptophan. All the bacterial strains were positive for ammonia production, cellulase and pectinase activity, but few of them showed phosphate solubilization, siderophore and hydrogen cyanide production. Only three strains showed ACC (1-aminocyclopropane-1-carboxylate) deaminase activity when tested using in-vitro enzyme assay. Members of genera Bacillus, Pseudomonas and Streptomyces showed positive chitinase, protease and antifungal activity against two phytopathogenic fungi Aspergillus niger and Fusarium oxysoprum, while members of Xanthomonas, Pseudomonas and Bacillus showed significant root elongation of Canola which could be related with their positive plant-growth-promoting (PGP) traits. Among the three plant growth promoting Bacillus strains, B. idriensis is never reported before for its PGP activities. These results showed the potential of Dodonaea viscosa endophytic bacteria as PGPBs, which in future can be further explored for their host range/molecular mechanisms.