BIODIVERSITY OF FLUORESCENT PSEUDOMONADS FROM THE RHIZOSPHERE SOILS OF REDGRAM AND MAIZE CROPS

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dc.contributor.advisorSUBHASH REDDY, R
dc.contributor.authorSUPRAJA, Y
dc.date.accessioned2016-06-07T14:19:38Z
dc.date.available2016-06-07T14:19:38Z
dc.date.issued2011
dc.description.abstractIn the present investigation, fluorescent pseudomonads were isolated from the rhizosphere of maize and redgram crop plants, since the microorganisms that grow in the rhizosphere provide defense for roots against the attack by plant pathogens. Thirty bacterial isolates were obtained from the 50 rhizosphere soil samples. Out of which, fifteen isolates were identified as fluorescent Pseudomonads based on their fluorescence nature under UV-light on Pseudomonas agar. To test the antagonistic potential of isolated fluorescent pseudomonads they were screened against two common soil borne fungi viz., Fusarium moniliforme and Macrophomina phaseolina under in vitro conditions using dual culture plate technique. In this study, Pseudomonas (RPF-5, MPF-4, RPF-7, RPF-4, MPF-6 and MPF-2) isolates showed highest potential for antagonism against Fusarium moniliforme. Three Pseudomonas isolates (RPF-5, MPF-6 and RPF-8) were found as potential antagonists for Macrophomina phaseolina. The two isolates RPF-5 and MPF-6 had the capacity to inhibit the growth of two fungal pathogens. Under field conditions, in addition to biocontrol agents, farmers use agrochemicals like fungicides, insecticides and herbicides etc. to control plant diseases, pests and weeds. Because of this, the potential antagonistic PF (fluorescent Pseudomonas) isolates were tested for their compatibility with the commonly used agrochemicals. All the agrochemicals were found to be compatible with the ten PF (RPF-1, RPF-2, RPF-3, RPF-4, RPF-5, RPF-7, RPF-8, MPF-2, MPF-4 and MPF-6) isolates. To know the nature of the antagonistic property of PF isolates, tests were conducted for the production of siderophores and Hydrogen cyanide (HCN). They were also examined for the production of Indole acetic acid (IAA) and solubilization of phosphate. It was observed that all the isolates, which showed antagonism against fungal pathogens, were also found positive for IAA and siderophore production. All the isolates showed phosphate solubilization except RPF-7 and MPF-4. Only RPF-5 and RPF-8 were positive for HCN production. In order to know the genetic similarity of isolated fluorescent Pseudomonads, RAPD analysis was carried out by using twenty operan series (OPL) primers. In this study, all the isolates were proved cent per cent polymorphic based on polymorphic bands formed and dendrogram analysis. At 61% similarity level 6 clusters were distinguished with 15 isolates of fluorescent Pseudomonas isolates by RAPD using twenty primers (OPL series). In that the best isolates RPF-5, RPF-8 and MPF-6 were assimilated in to different clusters. RPF-5 formed a separate major subgroup with 59 per cent similarity coefficient. RPF-5 was best isolate in the present study for production of IAA, siderophore, HCN and phosphate solubilization. It exhibited antagonistic activity against Fusarium moniliforme and Macrophomina phaseolina. Another best isolate, MPF-6 belongs to 2nd cluster could produce Indole acetic acid, siderophores and phosphate solubilization ability. RPF-8, isolate formed 5th cluster. It showed similar qualities like RPF-5. Eventhough these three isolates showed similar qualities but variability is higher among these three isolates. It means that the genotypic and phenotypic diversity of P. fluorescens could be based on the geographic origin and functional differences in the genome of the isolates. At 55 per cent similarity coefficient all the fifteen isolates are genetically relateden_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/66950
dc.language.isoenen_US
dc.publisherACHARYA N.G. RANGA AGRICULTURAL UNIVERSITYen_US
dc.relation.ispartofseriesD8847;
dc.subAgricultural Microbiology
dc.subjectbacteria, fungi, diseases, planting, biological development, inorganic acid salts, productivity, biochemical compounds, pathogens, rapden_US
dc.these.typeM.Sc
dc.titleBIODIVERSITY OF FLUORESCENT PSEUDOMONADS FROM THE RHIZOSPHERE SOILS OF REDGRAM AND MAIZE CROPSen_US
dc.typeThesisen_US
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