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

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Title BIODIVERSITY OF FLUORESCENT PSEUDOMONADS FROM THE RHIZOSPHERE SOILS OF REDGRAM AND MAIZE CROPS
 
Creator SUPRAJA, Y
 
Contributor SUBHASH REDDY, R
 
Subject bacteria, fungi, diseases, planting, biological development, inorganic acid salts, productivity, biochemical compounds, pathogens, rapd
 
Description In 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 related
 
Date 2016-06-07T14:19:38Z
2016-06-07T14:19:38Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/66950
 
Language en
 
Relation D8847;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY