Biocontrol bacteria selected by a direct plant protection strategy against avocado white root rot show antagonism as a prevalent trait

• Published in: Journal of applied microbiology Vol. 109; no. 1; pp. 65 - 78
• Main Authors: González-Sánchez, M.Á, Pérez-Jiménez, R.M, Pliego, C, Ramos, C, de Vicente, A, Cazorla, F.M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.07.2010; Blackwell Publishing Ltd; Blackwell; Oxford University Press
• Subjects: agriculture; Antagonism; Antibiosis; Bacillus; Bacillus - growth & development; Bacillus - isolation & purification; Bacteria; biocontrol; Biofilms; Biological and medical sciences; Biological control; Crops, Agricultural - microbiology; Fruit trees; Fundamental and applied biological sciences. Psychology; mechanism of action; Microbiology; Persea - microbiology; Persea americana; plant diseases; Plant Diseases - microbiology; Plant Diseases - prevention & control; plant diseases and disorders; plant pathology; Plant protection; Plant Roots - microbiology; Pseudomonas; Pseudomonas - growth & development; Pseudomonas - isolation & purification; Rhizosphere; Root rot; Soil Microbiology; Strains (organisms); Xylariales - pathogenicity; Antagonism; Disease; Root; Applied microbiology; Biological control; Bacteria; Agriculture; plant diseases; Mechanism of action; Protection; biocontrol; plant pathology
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2009.04628.x

This study was undertaken to study bacterial strains obtained directly for their efficient direct control of the avocado white root rot, thus avoiding prescreening by any other possible mechanism of biocontrol which could bias the selection. A collection of 330 bacterial isolates was obtained from the roots and soil of healthy avocado trees. One hundred and forty-three representative bacterial isolates were tested in an avocado/Rosellinia test system, resulting in 22 presumptive protective strains, all of them identified mainly as Pseudomonas and Bacillus species. These 22 candidate strains were screened in a more accurate biocontrol trial, confirming protection of some strains (4 out of the 22). Analyses of the potential bacterial traits involved in the biocontrol activity suggest that different traits could act jointly in the final biocontrol response, but any of these traits were neither sufficient nor generalized for all the active bacteria. All the protective strains selected were antagonistic against some fungal root pathogens. Diverse bacteria with biocontrol activity could be obtained by a direct plant protection strategy of selection. All the biocontrol strains finally selected in this work were antagonistic, showing that antagonism is a prevalent trait in the biocontrol bacteria selected by a direct plant protection strategy. This is the first report on the isolation of biocontrol bacterial strains using direct plant protection strategy in the system avocado/Rosellinia. Characterization of selected biocontrol bacterial strains obtained by a direct plant protection strategy showed that antagonism is a prevalent trait in the selected strains in this experimental system. This suggests that antagonism could be used as useful strategy to select biocontrol strains.