Journal of Applied Microbiology (2007) 103, 1007-1020

M. Perneel, J. Heyrman, A. Adiobo, K. De Maeyer, J.M. Raaijmakers, P. De Vos and M. Höfte (2007)
Characterization of CMR5c and CMR12a, novel fluorescent Pseudomonas strains from the cocoyam rhizosphere with biocontrol activity
Journal of Applied Microbiology 103 (4), 1007-1020
Abstract: Aim: To screen for novel antagonistic Pseudomonas strains producing both phenazines and biosurfactants that are as effective as Pseudomonas aeruginosa PNA1 in the biocontrol of cocoyam root rot caused by Pythium myriotylum.
Material and Results: Forty pseudomonads were isolated from the rhizosphere of healthy white and red cocoyam plants appearing in natural, heavily infested fields in Cameroon. In vitro tests demonstrated that Py. myriotylum antagonists could be retrieved from the red cocoyam rhizosphere. Except for one isolate, all antagonistic isolates produced phenazines. Results from whole-cell protein profiling showed that the antagonistic isolates are different from other isolated pseudomonads, while BOX-PCR revealed high genomic similarity among them. 16S rDNA sequencing of two representative strains within this group of antagonists confirmed their relatively low similarity with validly described Pseudomonas species. These antagonists are thus provisionally labelled as unidentified Pseudomonas strains. Among the antagonists, Pseudomonas CMR5c and CMR12a were selected because of their combined production of phenazines and biosurfactants. For strain CMR5c also, production of pyrrolnitrin and pyoluteorin was demonstrated. Both CMR5c and CMR12a showed excellent in vivo biocontrol activity against Py. myriotylum to a similar level as Ps. aeruginosa PNA1.
Conclusion: Pseudomonas CMR5c and CMR12a were identified as novel and promising biocontrol agents of Py. myriotylum on cocoyam, producing an arsenal of antagonistic metabolites.
Significance and Impact of the Study: Present study reports the identification of two newly isolated fluorescent Pseudomonas strains that can replace the opportunistic human pathogen Ps. aeruginosa PNA1 in the biocontrol of cocoyam root rot and could be taken into account for the suppression of many plant pathogens.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Monica Höfte

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
surveys/distribution/isolation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pythium myriotylum	Cocoyam (Xanthosoma)
Pseudomonas (genus - antagonists)	Pythium myriotylum	Cocoyam (Xanthosoma)