Evaluating the diversity and phylogeny of plant growth promoting bacteria associated with wheat (Triticum aestivum) growing in central zone of India

Abstract

The diversity of plant growth promoting bacteria was investigated from wheat growing in different sites in central zone of India. Epiphytic, endophytic and rhizospheric bacteria were isolated using different growth medium. Bacterial diversity was analysed through amplified ribosomal DNA restriction analysis (ARDRA) using three restriction enzymes Alu I, Hae III, and Msp I which led to the grouping of 348 isolates into 24-29 clusters at >75% similarity index. 16S rRNA gene based phylogenetic analysis, revealed that 134 strains belonged to three phyla namely actinobacteria, firmicutes and proteobacteria with 38 distinct species of 17 genera. Bacillus and Pseudomonas were dominant in rhizosphere while Methylobacterium were in phyllosphere. Endophytic niche specific bacteria were identified as Delftia and Micrococcus. Sampling of different sites showed variation in diversity indices. In vitro plant growth promoting activities of bacteria exposed more than three beneficial traits which may act independently or concurrently. Phosphate solubilization and siderophores production are the predominant traits exhibited by these microbes. The many species of genera Bacillus, Exiguobacterium, Micrococcus, Pseudomonas and Psychrobacter showed antagonistic properties against fungal pathogens Fusarium graminerum, Rhizoctonia solani and Macrophomina phaseoli. These promising isolates showing a range of useful plant growth promoting attributes insist to be explored for agricultural applications.