Isolation and screening of phlD+ plant growth promoting rhizobacteria antagonistic to Ralstonia solanacearum

• Published in: World journal of microbiology & biotechnology 2012-04, Vol.28 (4), p.1681-1690
• Main Authors: Ramadasappa, Srinivasamurthy, Rai, Ashwani K., Jaat, Ranjeet Singh, Singh, Aqbal, Rai, Rhitu
• Format: Article
• Language: English
• Subjects: Acetic acid; Acids; Agricultural biotechnology; Alphaproteobacteria - genetics; Alphaproteobacteria - isolation & purification; Alphaproteobacteria - physiology; Antibiosis; Antibiotics; Applied Microbiology; Bacteria; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Biochemistry; Biological control; Biomass; Biomedical and Life Sciences; Biotechnology; Cluster Analysis; Crop diseases; Crops; Disease control; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; DNA, Ribosomal - chemistry; DNA, Ribosomal - genetics; E coli; Environmental Engineering/Biotechnology; Genetic diversity; India; Infections; Life Sciences; Lycopersicon esculentum - growth & development; Lycopersicon esculentum - microbiology; Mass Screening - methods; Metabolites; Microbiology; Original Paper; Pathogens; Phylogeny; Plant diseases; Plant Diseases - microbiology; Plant Diseases - prevention & control; Plant growth; Polymerase Chain Reaction - methods; Ralstonia solanacearum - growth & development; Ralstonia solanacearum - pathogenicity; Ribosomal DNA; RNA, Ribosomal, 16S - genetics; Sequence Analysis, DNA; Studies; Tomatoes
• ISSN: 0959-3993; 1573-0972
• DOI: 10.1007/s11274-011-0975-0

Tomato ( Lycopersicon esculentum ) is important widely grown vegetable in India and its productivity is affected by bacterial wilt disease infection caused by Ralstonia solanacearum. To prevent this disease infection a study was conducted to isolate and screen effective plant growth promoting rhizobacteria (PGPR) antagonistic to R. solanacearum . A total 297 antagonistic bacteria were isolated through dual culture inoculation technique, out of which forty-two antagonistic bacteria were found positive for phlD gene by PCR amplification using two primer sets Phl2a:Phl2b and B2BF:BPR4. The genetic diversity of phlD + bacteria was studied by amplified 16S rDNA restriction analysis and demonstrated eleven groups at 65% similarity level. Out of these 42 phlD + antagonistic isolates, twenty exhibited significantly fair plant growth promoting activities like phosphate solubilization (0.92–5.33%), 25 produced indole acetic acid (1.63–7.78 μg ml −1 ) and few strains show production of antifungal metabolites (HCN and siderophore). The screening of PGPR ( phlD + ) for suppression of bacterial wilt disease in glass house conditions was showed ten isolated phlD + bacteria were able to suppress infection of bacterial wilt disease in tomato plant (var. Arka vikas ) in the presence R. solanacearum . The PGPR ( phlD + ) isolates s188, s215 and s288 was observed to be effective plant growth promoter as it shows highest dry weight per plant (3.86, 3.85 and 3.69 g plant −1 respectively). The complete absence of wilt disease symptoms in tomato crop plants was observed by these treatments compared to negative control. Therefore inoculation of tomato plant with phlD + isolate s188 and other similar biocontrol agents may prove to be a positive strategy for checking wilt disease and thus improving plant vigor.