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The search for beneficial endophytes that can be part of a constructed microbial community has increased in recent years. We characterized three endophytic fungi previously isolated from wheat for their in vitro and in planta antagonism toward the Fusarium head blight pathogen, Fusarium graminearum. The endophytes were phylogenetically characterized and shown to be Alternaria destruens, Fusarium commune, and Fusarium oxysporum. Individual fungal endophytes significantly increased seed weight and lowered the accumulation of the mycotoxin deoxynivalenol compared to F. graminearum infected wheat heads without endophyte pretreatment. Investigation into the mechanism of competition in vitro showed that endophytes competitively excluded F. graminearum by pre-emptive colonization and possible inhibition over a distance. Investigations on the use of these endophytes in the field are in progress. Identification of these three endophytes highlights a common quandary in searching for beneficial microbes to use in agriculture: species definitions often do not separate individual isolates’ lifestyles. A greater understanding of the risks in using intraspecies variants for biocontrol is needed and should be examined in the context of the ecology of the individuals being investigated.

For many plant pathogenic or endophytic fungi, production of mycotoxins, which are toxic to humans, may present a fitness gain. However, associations between mycotoxin production and plant pathogenicity or virulence is inconsistent and difficult due to the complexity of these host-pathogen interactions and the influences of environmental and insect factors. Aflatoxin receives a lot of attention due to its potent toxicity and carcinogenicity, but the connection between aflatoxin production and pathogenicity is complicated by the pathogenic ability and prevalence of n on-aflatoxigenic isolates in crops. Other toxins directly aid fungi in planta, trichothecenes are important virulence factors and ergot alkaloids limit herbivory and fungal consumption due to insect toxicity. We review a panel discussion at Amercian Phytopathological Society's Plant Health 2021 conference, which gathered diverse experts representing different research sectors, career stages, ethnicities and genders to discuss the diverse roles of mycotoxins in the lifestyles of filamentous fungi of the families: Clavicipitaceae, Trichocomaceae (Eurotiales), Nectriaceae (Hypocreales).

The active ingredient prothioconazole is a demethylase inhibitor (DMI) widely used in numerous commercial fungicide formulations for crop protection. However, prothioconazole converts in planta to prothioconazole-desthio, which was found to be the primary active form inhibiting CYP51 activity in fungi. Here, experiments were performed on Fusarium graminearum to compare the use of technical-grade prothioconazole-desthio, technical-grade prothioconazole, and formulated product Proline in poison-plate mycelial growth assays to investigate the relevancy of using prothioconazole for sensitivity testing. Prothioconazole-desthio was significantly more efficacious at mycelial growth inhibition than prothioconazole but mycelial growth and effective concentration to reduce growth by 50% (EC50) values between the two correlated significantly. Although care should be taken in interpreting EC50 values of prothioconazole, the compound is still suitable for monitoring sensitivity rather than purchasing the more expensive prothioconazole-desthio.

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