Antagonistic activity of Bacteria from the chickpea rhizosphere againstFusarium Oxysporum f. sp.Ciceris

Abstract

The antagonistic activity against in vitro growth of Fusarium oxysporum f.sp. ciceris was determined for 74 bacterial isolates obtained from the rhizosphere of chickpeas grown in two field soils with different histories of Fusarium wilt, and for seven isolates of Pseudomonas spp. from culture collections. 1\venty-four isolates of Bacillus spp. and Pseudomonas chlororaphis 30-84 showed a strong antagonism against three races (0, 1 and 5) of F.o. ciceris tested. Three selected Bacillus isolates and P. chlororaphis 30-84 were further tested against 30 isolates of races O, 1 and 5 of F.o. ciceris, races O, 1 and 2 of F.o. melonis, F.o. phaseoli and nonpathogenic F. oxysporum. Bacillus isolates differed in their antagonistic activity and were less inhibitory to mycelial growth of F.o. eiceris than to that of other fungai isolates. Furthermore, the extent of growth inhibition of F.o. ciceris was influenced both by bacterial isolates and by race of the pathogen. Cell-free culture filtrates of four Bacillus isolates inhibited conidial germination and hyphal growth of F.o. ciceris and nonpathogenic F. oxysporum. Joint seed+soil treatment with some selected antagonistic Bacillus spp. isolates suppressed disease caused by the highly virulent F.o. ciceris race-5 in cv. ICCV 4 and cv. PV 61 chickpeas. However, the degree o f protection was influenced by the host genotype and the inoculum concentration of the pathogen.

Screening rhizobacteria for biological control of Fusarium root and crown rot of sorghum in Ethiopia

“…1) suggesting that the rhizobacteria could be producing certain antifungal metabolites (AFMs) (Montealegre et al, 2003). Moreover, as the PDA medium used for the dual culture assay is rich in nutrients, competition might be excluded as the mode of action for these isolates (Landa et al, 1997). The antifungal metabolites produced seem to vary among the isolates tested in this study.…”

“…The bacterial isolates used were initially isolated from the rhizosphere of sorghum plants in the major sorghum growing fields in Ethiopia. The approach provided an opportunity to select effective biocontrol strains capable of antagonizing soilborne pathogens in the same environment where they will be used commercially (Landa et al, 1997). Moreover, isolation of bacteria from within the rhizosphere of the target crop is essential for successful identification of potential biocontrol agents (Williams and Asher, 1996).…”

“…Among the potential biocontrol agents active in the rhizosphere, several members of the Genus Bacillus are reported to be effective in controlling a variety of fungal plant diseases (Williams and Asher, 1996, Landa et al, 1997and Commare et al, 2002 (Landa et al, 1997).…”

“…The in vitro inhibition of mycelial growth of F. oxysporum by the bacterial isolates was tested using the dual culture technique as described by Paulitz et al, 1992 andLanda et al, 1997. Three 50 μl drops from the 10 8 cfu/ml suspension were equidistantly placed on the margins of potato dextrose agar (PDA) (BioLab) plates and incubated at 28 °C for 24 h. A 4 mm agar disc from fresh PDA cultures of F. oxysporum was placed at the centre of the PDA plate for each bacterial isolate and incubated at 27 ± 1 °C for seven days.…”

Phosphate solubilization and multiple plant growth promoting properties of rhizobacteria isolated from chickpea (Cicer aeritinum L.) producing areas of Ethiopia

“…ciceri (FOC) growth inhibition activity of the PSB isolates was tested using the dual culture technique (Landa et al, 1997). 20 µl of bacterial culture grown in nutrient broth to the exponential phase was equidistantly spotted on the margins of nutrient agar (NA) plates amended with glucose (1.0%) and incubated at 30°C.…”