5266
USAMA SAMY FATHY MOHAMED ELKELANY
CONTROLLING OF ROOT-KNOT NEMATODES IN EGGPLANTS USING GENETICALLY IMPROVED BACTERIA
Protoplast fusion - Gene cloning- chitinase -Meloidogyne javanica – Eggplant - Rhizobacteria.
Meloidogyne javanica is one of the major pest infecting eggplants, the important vegetable crop in Egypt. The world wide control of root-knot nematodes depends on the use of synthetic nematicides. Due to the high cost and toxicity of the chemical nematicides, alternative control measures have been investigated. One plausible alternative is the use of biocontrol strategies which involves the application of antagonistic microbes to nematodes. The most common microorganisms involved in this strategy are soil bacteria named rhizobacteria. The objectives of this study are to improve the nematicidal potential of selected rhizobacterial strains against M. javanica infecting eggplant through biotechnological process i.e. protoplast fusion and gene cloning. The study was started with the screening of sixteen identified rhizobacterial strains Anoxybacillus flavithermus - Bacillus alvea N3- B. cereus Bc6 - B. cereus 6A15- B. cereus I/6 - B. licheniformis N5– B. licheniformis 5A3- B. pumilus I1- B. subtilis Ain-shams -B. subtilis D.B100 – B. subtilis Al-Azhar -B. thuringiensis I.B -B. thuringiensis I.A -B. thuringiensis K - Geobacillus stearothermophilus 9A5 and Pseudomonas fluorescens against M. javanica J2s. The highly percentage mortality in M. javanica J2s were 87.5% and 84.09 % resulted from A. flavithermus and B. pumilus, respectively after three days of exposure time. Under laboratory conditions, bioassay tests were carried out to evaluate the egg hatch inhibition and mortality effect on M. javanica J2s due to cell suspension of A. flavithermus, B. pumilus, B. subtilus, B. thuringiensis and P. fluorescens. The greatest inhibition of egg hatch percentage was 87.69%due to A. flavithermus and the highly recorded percentage mortality in M. javanica J2s (86.15%) was due to B. subtilus, as compared to control. Thegreenhouse experiment using root dip treatment for 20 min in 10 ml (2 × 106cfu/ml) cell suspension for the five aforementioned rhizobacterial strains simultaneously and one week before nematode infection, showed a significant suppression effect for all strains on nematode reproduction with an improvement in eggplant growth parameters, as compared to control. Data revealed that root dipping one week before nematode infection, was more promising than that of treated simultaneously. The pot experiment conducted to study the effect of drenching the soil with 10 ml (2 × 106cfu/ml) cell suspension of the aforementioned rhizobacterial strains using three times of application relatively to nematode infection (simultaneously, one week before and one week after) revealed that, all treatments significantly reduced M. javanica population in soil and roots and improved eggplant growth parameters.
2016
Ph.d
Ain Shams
Agriculture