Title : Isolation and molecular characterization of Pseudomonas species and its effect on rooting in crops
Fluorescent Pseudomonads belong to plant Growth Promoting Rhizobacteria (PGPR), the important group of bacteria that play a major role in the plant growth promotion, induced systemic resistance, biological control of pathogens etc. Many strains of Pseudomonas fluorescens are known to enhance plant growth promotion and reduce severity of various diseases .This investigation was carried out to study the molecular and physiological characterization of Pseudomonas species isolated from different locations of Tumakuru district and its effects on the root growth of Ground nut and Finger millet. Pseudomonas strains from different locations were isolated, identified and confirmed as Pseudomonas fluorescens using standard synaptic keys. These included microscopic observation, biochemical and physiological characters like oxidase test, catalase test, casein hydrolysis test, starch hydrolysis and growth studies at 4oC and 41oC. Isolates were identified and characterized as Pseudomonas fluorescens. Molecular diversity of these isolates were characterized by 16S rDNA universal primers analysis, out of twelve isolates best performing six isolates for root growth were sent for sequencing and the sequence obtained were compared against sequences on the GenBank at the NCBI website. Analysis of the sequences by BLAST tool on the NCBI website indicated that isolate PS-GN, PS-T, PS-FM matched 97% with Pseudomonas fluorescens. Simultaneously plant growth response studies using groundnut and fingermillet as host were conducted. In plants inoculated with P. fluorescens isolates, the root lengtht, fresh and dry weight of roots, remained higher than the uninoculated plants. In the experiment conducted, isolates of rhizospheric soil selected from ground nut (PS-GN) tomato rhizospheric soil (PS-T) and fingermillet rhizospheric soil (PS-FM) performed well compared to other isolates with respect to all the parameters mentioned above.