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Antagonistic Activity of Pseudomonas fluorescens Strain X1 Against Different Fusaria and it's In Vivo Analysis
Nellie Laisram1, Zeeshanur Rahman2, Ved Pal Singh3
1Department of Botany, Dyal Singh College, University of Delhi, New Delhi, 110003, India.
Abstract:
A plant growth-promoting rhizobacterial strain, Pseudomonas fluorescens X1 isolated from the garden soil was employed for antagonistic activity against different species of fusaria. Strain X1 inhibited four different fusaria (Fusarium moniliforme, Fusarium oxysporum, Fusarium semitectum and Fusarium udum) in dual culture plate assay, and in broth culture using cell-free culture filtrate. Scanning electron microscopic (SEM) analysis revealed deformation and shrinkage in mycelia of fusaria after treatment with strain X1. Confocal micrographs showed degeneration of nuclei inside the cells of fusaria for the same effect. Strain X1 exhibited maximum antifungal activity, when it was grown in nutrient broth yeast (NBY) medium amended with 1 mM NH4MoO4 and 1% glucose. The antifungal extracts eluted from thin-layer chromatography (TLC) followed by high performance liquid chromatography (HPLC) showed two fractions active against different fusaria. Liquid chromatography-mass spectrometry (LCMS) analysis of the two fractions 1 and 2 corresponded to molecular ions at m/z 177.16 and m/z 177.09, respectively. Infra-red (IR) analysis showed five similar absorption bands in both the fractions analysed. In vivo analysis of strain X1 alone and along with fungicide inhibited the growth of F. udum and improved the biomass and growth of pigeon pea. These results indicated that strain X1 could be possibly used as a biocontrol agent to inhibit the growth of soil-borne diseases of different fusaria including F. udum that causes wilting in pigeon pea.
Insights
Pseudomonas fluorescens X1 effectively inhibits harmful fusaria species, showing potential as a biocontrol agent for plant diseases. This rhizobacterium enhances pigeon pea growth and biomass, offering a sustainable solution for agriculture.
Area of Science:
- Microbiology
- Plant Pathology
- Biotechnology
Background:
- Soil-borne fungal diseases caused by Fusarium species pose significant threats to crop production.
- Plant growth-promoting rhizobacteria (PGPR) offer a sustainable alternative for disease management.
Purpose of the Study:
- To evaluate the antagonistic potential of Pseudomonas fluorescens X1 against various Fusarium species.
- To investigate the mechanisms of antifungal activity and optimize conditions for PGPR efficacy.
- To assess the in vivo performance of Pseudomonas fluorescens X1 in controlling Fusarium udum and promoting pigeon pea growth.
Main Methods:
- Dual culture and broth culture assays were used to assess antifungal activity.
- Scanning electron microscopy (SEM) and confocal microscopy were employed to observe cellular damage in Fusarium.
- Optimized growth conditions (NBY medium with NH4MoO4 and glucose) were determined.
- Antifungal compounds were isolated and characterized using TLC, HPLC, LCMS, and IR spectroscopy.
- In vivo studies were conducted on pigeon pea plants infected with Fusarium udum.
Main Results:
- Pseudomonas fluorescens X1 demonstrated significant inhibition of Fusarium moniliforme, F. oxysporum, F. semitectum, and F. udum.
- SEM and confocal microscopy revealed mycelial deformation, shrinkage, and nuclear degeneration in Fusarium species.
- Maximum antifungal activity was observed in NBY medium supplemented with 1 mM NH4MoO4 and 1% glucose.
- Two active antifungal fractions were isolated and characterized.
- In vivo application of strain X1 improved pigeon pea biomass and growth while inhibiting F. udum.
Conclusions:
- Pseudomonas fluorescens X1 is a potent biocontrol agent against Fusarium species.
- The bacterium exerts its antifungal effects through direct antagonism and cellular damage.
- Optimized growth conditions enhance the production of antifungal compounds.
- Strain X1 shows promise for managing soil-borne diseases and promoting crop growth in agricultural settings.
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