Abstract
Fusarium graminearum and F. culmorum are the causing agents of a destructive disease known as Fusarium head blight (FHB). FHB is a re-emerging disease in small grain cereals which impairs both the grain yield and the quality. Most serious consequence is the contamination of grain with Fusarium mycotoxins that are severe threat to humans and animals. Biological control has been suggested as one of the integrated management strategies to control FHB. Paenibacillus polymyxa is considered as a promising biocontrol agent due to its unique antibiotic spectrum. P. polymyxa A26 is an efficient antagonistic agent against Fusarium spp. In order to optimize strain A26 production, formulation and application strategies traits important for its compatibility need to be revealed. Here we developed a toolbox, comprising of dual culture plate assays and wheat kernel assays, including simultaneous monitoring of FHB causing pathogens, A26, and mycotoxin production. Using this system we show that, besides generally known lipopeptide antibiotic production by P. polymyxa, biofilm formation ability may play a crucial role in the case of stain A26 F. culmorum antagonism. Application of the system for effective strain selection and maintenance is discussed.
Highlights
Fusarium head blight (FHB) is a destructive disease on cereals that is caused by a group of Fusarium species including Fusarium graminearum and F. culmorum (Nazari et al, 2014)
To study the mode of action of strain A26, we developed a method for A26 mutagenesis (Kim and Timmusk, 2013) and inactivated the A26 Sfp-type phosphopantheinyl transferase (PPTase) gene resulting in a deletion mutation that is deficient in the production of non-ribosomal peptides (NRP) and PK origin antibiotics and has lost its antagonistic activity on plate assays
The results presented here show that SFS strain A26 is highly effective in antagonizing F. graminearum and F. culmorum on the plate assay in comparison to the NFS strain E1 that was tested (Table 2)
Summary
Fusarium head blight (FHB) is a destructive disease on cereals that is caused by a group of Fusarium species including Fusarium graminearum and F. culmorum (Nazari et al, 2014). FHB is a major threat to agricultural production due to yield losses, and constitutes a major safety concern when humans and animals consume Fusarium-contaminated products due to the accumulation of several mycotoxins (Yazar and Omurtag, 2008; Xiao et al, 2013). Both F. culmorum and F. graminearum are soil borne and cause FHB, and Fusarium foot and root rot on cereals around the globe especially during wet seasons (Scherm et al, 2013). Higher levels of both toxins in wheat grains are usually connected to infection with F. culmorum or F. graminearum (Fredlund et al, 2013; Lindblad et al, 2013).
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