Pseudomonas simiae effects on the mycotoxin formation by fusaria and alternaria in vitro and in a wheat field
Fluorescent pseudomonads colonizing wheat ears have a high antagonistic potential against phytopathogenic fungi. To check this hypothesis, the bacterial antagonist Pseudomonas simiae 9 rif+/kan+ was spray-inoculated onto the ears of winter wheat in a locally demarcated experimental field plot. Fusarium and Alternaria fungi naturally occurring on the ears and the formation of their mycotoxins in the ripe grains were investigated. Inoculated bacteria were recovered from the plants in the inoculation cell, but not in the untreated neighboring plots or in the air above the plants. Growth of fusaria and alternaria on the ears was not influenced by the bacterial antagonist. Wheat kernels were co-inoculated in vitro with the antagonist and one mycotoxin-producing strain of Fusarium and Alternaria, respectively. Mycotoxin production was almost completely suppressed in these approaches. Concentrations of zearalenone, deoxynivalenol, alternariol, and tenuazonic acid were also significantly reduced in ripe grains in the field, but to a lesser extent than in vitro. The results of this and previous studies suggest that widespread biological control of the growth of fusaria and alternaria and their mycotoxin formation by naturally occurring pseudomonads with antagonistic activity is rather unlikely.
KeywordsBiological control Wheat Pseudomonas Fusarium Alternaria Mycotoxins
Alternariol monomethyl ether
High-performance liquid chromatography
Microbial biocontrol agents
We thank Petra Lange, Martina Peters, and Grit von der Waydbrink, for excellent technical assistance.We are also grateful to E. Garcia-Valdes and J. Lalucat (Balearic Islands University) for rpoD gene sequencing of the antagonist used in this study.
Source of funding
This work was financially supported by Deutsche Forschungsgemeinschaft in the framework of the BioMove Research Training Group (DFG-GRK 2118/1).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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