Molecular characterization of plant growth promoting bacterial strains from Pinus roxburghii L. rhizosphere

Present study deals with the isolation and characterization of twenty five bacterial strains from the rhizosphere of Pinus roxburghii growing in three different geographical regions (Lahore, Islamabad and Mansehra) of Pakistan. Out of twenty five isolates, eight (32%) solubilized tri-calcium phosphate (TCP), nine (36%) produced plant growth hormone indole acetic acid (IAA), five (20%) produced anti-fungal metabolites and ten (40%) produced siderophores. On the basis of 16S rRNA gene sequences, thirteen Gram-positive (52%) and twelve Gram-negative (48%) isolates were assigned to ten genera and twenty one species. Of these genera, Bacillus (five species) made up the largest complement followed by Pseudomonas (two species). The Gram-negative rhizobacteria were distributed in two phyla: Proteobacteria (alpha-proteobacteria, gamma-proteobacteria) and Flavobacteria. Plant growth experiment study revealed that strains (Comamonas sp., Enterobacter sp., Bacillus simplex, Bacillus sp., Pantoea sp. and Pseudomonas aeruginosa) were able to enhance wheat root length to a significant level (up to 47%) as compared to non-inoculated control.