Novel Plant Growth Promoting Rhizobacteria from Rhizospheres of Date Palm (Phoenix dactylifera): 16S rRNA Typing and Phylogenetic Analyses Reveal their Distinct Identity

Abstract

Abstract

Plant growth-promoting rhizobacteria (PGPR) comprise a large portion of soil microbiome and are essential for the growth of plants as they are capable of exhibiting a range of plant growth promoting biochemical mechanisms. Reports on rhizosphere microflora of date palm tree Phoenix dactylifera are scarce and the rhizomicrobiome of the date palm tree is expected to have microbial members that exhibit features to overcome stress due to varying conditions such as drought, salinity, nutrient deficiency of soil, etc. Hence, this study is attempted to explore and characterize the structural and functional attributes of rhizosphere of Phoenix dactylifera in detail by means of analyzing physicochemical parameters of rhizosphere soils collected from two different fertile date palm cultivation sites; investigating the bacterial profile of rhizobiome by conducting studies on isolation, identification, microbiological and biochemical characterization, and 16S rRNA genotyping of PGPR; and further examining the phylogenetic relations of the isolated bacteria with their closest members using bioinformatic tools and screening for PGP activity through analysis of various functions and assays. Phylogenetic studies on 16S rRNA of the bacterial isolates reveal that these strains are novel, as they do not share 100% homology with that of the isolates deposited in the GenBank of NCBI. However, they exhibit close relationship with the members of same genus or members of different taxonomic groups. Several of these bacterial members are found to present predominantly in samples of both the sampling sites suggesting that these microorganisms may be unique to date palm tree rhizosphere. The novel PGPR members of the date palm tree provide ideal environment for the plant to survive in varied soil conditions due to their range of plant growth promoting (PGP) features and can be the constituents of PGPR formulation to address the challenges of productivity.

Keywords: Phoenix dactylifera, plant growth-promoting rhizobacteria, 16S rRNA typing, Exiguobacterium, Kocuria, Janibacter anophelis

Cite this Article

S. Thennarasu, E. Natarajan, B. Muthukumar. Novel Plant Growth Promoting Rhizobacteria from Rhizospheres of Date Palm (Phoenix dactylifera): 16S rRNA Typing and Phylogenetic Analyses Reveal their Distinct Identity. Research & Reviews: A Journal of Microbiology and Virology. 2019; 9(1): 10–24p.