Combining biocontrol agents with different mechanisms of action in a strategy to control Botrytis cinerea on grapevine

Two biocontrol agents, a yeast (Pichia guilermondii) and a bacterium (Bacillus mycoides), were tested separately and together for suppression of Botrytis cinerea on strawberry leaves and plants. Scanning electron microscopy revealed significant inhibition of Botrytis cinerea conidial germination in the presence of Pichia guilermondii, whereas Bacillus mycoides caused breakage and destruction of conidia. When both biocontrol agents were applied in a mixture, conidial destruction was more severe. The modes of action of each of the biocontrol agents were elucidated and the relative quantitative contribution of each mechanism to suppression of Botrytis cinerea was estimated using multiple regression with dummy variables. The improvement in control efficacy achieved by introducing one or more mechanisms at a time was calculated. Pichia guilermondii competed with Botrytis cinerea for glucose, sucrose, adenine, histidine, and folic acid. Viability of the yeast cells played a crucial role in suppression of Botrytis cinerea and they secreted an inhibitory compound that had an acropetal effect and was not volatile. Bacillus mycoides did not compete for any of the sugars, amino acids, or vitamins examined at a level that would affect Botrytis cinerea development. Viable cells and the compounds secreted by them contributed similarly to Botrytis cinerea suppression. The bacteria secreted volatile and non-volatile inhibitory compounds and activated the defense systems of the host. The nonvolatile compounds had both acropetal and basipetal effects. Mixture of Pichia guilermondii and Bacillus mycoides resulted in additive activity compared with their separate application. The combined activity was due to the summation of biocontrol mechanisms of both agents. This work provides a theoretical explanation for our previous findings of reduced disease control variability with a mixture of Pichia guilermondii and Bacillus mycoides.

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Use of molecular techniques to elucidate the mechanisms of action of fungal biocontrol agents: A review

Journal of Microbiological Methods ◽

10.1016/j.mimet.2006.09.010 ◽

2007 ◽

Vol 69 (2) ◽

pp. 229-241 ◽

Cited By ~ 33

Author(s):

Sébastien Massart ◽

Haissam M. Jijakli

Keyword(s):

Mechanisms Of Action ◽

Molecular Techniques ◽

Biocontrol Agents

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Biocontrol Activity of Bacillus spp. and Pseudomonas spp. Against Botrytis cinerea and Other Cannabis Fungal Pathogens

Phytopathology ◽

10.1094/phyto-03-21-0128-r ◽

2021 ◽

Author(s):

Carole Balthazar ◽

Amy Novinscak ◽

Gabrielle Cantin ◽

David L. Joly ◽

Martin Filion

Keyword(s):

Botrytis Cinerea ◽

Fungal Pathogens ◽

De Novo ◽

Wide Spectrum ◽

Gene Clusters ◽

Gray Mold ◽

Control Measures ◽

Biocontrol Agents ◽

Effective Control ◽

In Planta

Gray mold caused by Botrytis cinerea is one of the most widespread and damaging diseases in cannabis crops worldwide. With challenging restrictions on pesticide use and few effective control measures, biocontrol agents are needed to manage this disease. The aim of this study was to identify and characterize bacterial biocontrol agents with wide-spectrum activity against B. cinerea and other major cannabis fungal pathogens. Twelve Bacillus and Pseudomonas strains were first screened with in vitro confrontational assays against ten culturable cannabis pathogens, namely B. cinerea, Sclerotinia sclerotiorum, Fusarium culmorum, F. sporotrichoides, F. oxysporum, Nigrospora sphaerica, N. oryzae, Alternaria alternata, Phoma sp. and Cercospora sp. Six strains displaying the highest inhibitory activity, namely B. velezensis LBUM279, FZB42, LBUM1082, B. subtilis LBUM979, P. synxantha LBUM223, and P. protegens Pf-5, were further assessed in planta where all, except LBUM223, significantly controlled gray mold development on cannabis leaves. Notably, LBUM279 and FZB42 reduced disease severity by at least half compared to water-treated plants and prevented lesion development and/or sporulation up to 9 days following pathogen inoculation. Genomes of LBUM279, LBUM1082 and LBUM979 were sequenced de novo and taxonomic affiliations were determined to ensure non-relatedness with pathogenic strains. Moreover, the genomes were exempt of detrimental genes encoding major toxins and virulence factors that could otherwise pose a biosafety risk when used on crops. Eighteen gene clusters of potential biocontrol interest were also identified. To our knowledge, this is the first reported attempt to control cannabis fungal diseases in planta by direct antagonism with beneficial bacteria.

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Inhibitory effect of lactoferrin against gray mould on tomato plants caused by Botrytis cinerea and possible mechanisms of action

International Journal of Food Microbiology ◽

10.1016/j.ijfoodmicro.2012.11.025 ◽

2013 ◽

Vol 161 (3) ◽

pp. 151-157 ◽

Cited By ~ 26

Author(s):

Jie Wang ◽

Xiao-Ming Xia ◽

Hong-Yan Wang ◽

Peng-Peng Li ◽

Kai-Yun Wang

Keyword(s):

Botrytis Cinerea ◽

Inhibitory Effect ◽

Mechanisms Of Action ◽

Tomato Plants ◽

Gray Mould

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Biological Control of Botrytis cinerea by Volatiles of ‘Isabella’ Grapes

Phytopathology ◽

10.1094/phyto.2004.94.9.924 ◽

2004 ◽

Vol 94 (9) ◽

pp. 924-931 ◽

Cited By ~ 14

Author(s):

Eleni K. Kulakiotu ◽

Constantine C. Thanassoulopoulos ◽

Evangelos M. Sfakiotakis

Keyword(s):

Botrytis Cinerea ◽

Inhibitory Action ◽

Fungal Growth ◽

Biological Action ◽

Biocontrol Agents ◽

Vitis Labrusca ◽

In Situ Study ◽

Antifungal Action

The effect of volatiles from cv. Isabella (Vitis labrusca) on the growth of Botrytis cinerea was tested in vitro and in situ, in the latter case on ‘Roditis’ grapes (V. vinifera), at various temperatures. The goal of the research was to determine whether the volatiles emitted by Isabella grapes could be effective biocontrol agents of Botrytis cinerea. The closed Mariotte system was used as a bioassay method to analyze quantitatively the biological action of these volatiles on fungal growth and disease development. The in vitro experiments revealed the inhibitory action of the Isabella volatiles on the sporulation and sclerotia formation of the fungus, as well as the stimulating action of the Roditis volatiles on the sporulation of the fungus. The in situ study confirmed the antifungal action of the Isabella volatiles as they reduced the inoculum and pathogenicity of B. cinerea. The antibiotic action was more pronounced at 21°C. The study indicates that Isabella volatiles act as biocontrol agents of B. cinerea.

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