Investigating Useful Properties of Four Streptomyces Strains Active against Fusarium graminearum Growth and Deoxynivalenol Production on Wheat Grains by qPCR.

Elena Maria Colombo,Cristina Pizzatti,Claudio Gardana,Matias Pasquali,Paolo Cortesi,Paolo Simonetti,Marco Saracchi,Andrea Kunova

doi:10.3390/toxins12090560

Abstract

Streptomyces spp. can be exploited as biocontrol agents (BCAs) against plant pathogens such as Fusarium graminearum, the main causal agent of Fusarium head blight (FHB) and against the contamination of grains with deoxynivalenol (DON). In the present research, four Streptomyces strains active against F. graminearum in dual plate assays were characterized for their ability to colonize detached wheat grains in the presence of F. graminearum and to limit DON production. The pathogen and BCA abundance were assessed by a quantitative real-time PCR, while DON production was assessed by HPLC quantification and compared to ergosterol to correlate the toxin production to the amount of fungal mycelium. Fungal growth and mycotoxin production were assessed with both co-inoculation and late inoculation of the BCAs in vitro (three days post-Fusarium inoculation) to test the interaction between the fungus and the bacteria. The level of inhibition of the pathogen and the toxin production were strain-specific. Overall, a higher level of DON inhibition (up to 99%) and a strong reduction in fungal biomass (up to 71%) were achieved when streptomycetes were co-inoculated with the fungus. This research enabled studying the antifungal efficacy of the four Streptomyces strains and monitoring their development in DON-inducing conditions.

Highlights

Fusarium head blight (FHB) is one of the most devastating cereal diseases, especially for wheat and barley
Our study contributes to deciphering the interactions occurring between Streptomyces strains a toxigenic strain of F. graminearum in a controlled environment, attempting a first characterization and a toxigenic strain of F. graminearum in a controlled environment, attempting a first of four promising Streptomyces strains to be used as biocontrol agents (BCAs) (Table 1)
Direct antifungal activity was characterization of four promising Streptomyces strains to be used as BCAs (Table 1)

Summary

Introduction

Fusarium head blight (FHB) is one of the most devastating cereal diseases, especially for wheat and barley. It is caused by a complex group of Fusarium spp., in which Fusarium graminearum is the main causal agent [1,2]. Severe yield losses occur in the field, together with a variable level of grain contamination with mycotoxins belonging to the group of type B trichothecenes, such as deoxynivalenol (DON) [3]. The fungal contamination in harvested grains can be kept under control during the storage period, but the mycotoxin incidence in feed and food products often increases. Toxins 2020, 12, 560 dramatically, becoming a threat for food and feed safety [4,5]. The toxic effects of DON include the alteration of intestinal, nervous, and immune systems due to the inhibition of protein synthesis and induction of apoptosis [7]

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Methods

Conclusion