Hunting for biological control agents: more fungal isolates than expected have promising properties

A mycoparasite is a fungus that attacks other fungi. Mycoparasitic relationships display a range from biotrophic, where nutrients are acquired from living host cells, to necrotrophic, where the fungal prey is killed and then consumed by the mycoparasite. Certain mycoparasitic strains are used as biological control agents against plant pathogenic fungi in agricultural fields. Biological control is a more sustainable and less hazardous alternative to the use of chemical pesticides.

Investigating the mechanisms behind biological control

- Of course, we want to maximize the benefits from mycoparasites in agriculture. In order to do that, we must learn more about the factors that affect what happens between the mycoparasite and the fungi that attack agricultural crops, says Magnus Karlsson.

In a new study, 11 whole fungal genomes from the mycoparasitic fungal genus Clonostachys have been examined.

– We looked at different gene families that we believe are playing a role in producing proteins that are involved in biological control.

How does it work in practice?

To investigate how it worked in practice, experiments were performed where wheat seeds were covered with spores of the various fungal species. The wheat seeds were placed in moist sand together with the pathogenic fungus Fusarium graminearum. This harmful fungus gives causes foot and root rot and head blight in cereal crops. In addition to crop reduction, head blight can lead to crops being contaminated by mycotoxins.

– The tested isolates of Clonostachys fungi were found to reduce the severity of the disease caused by the Fusarium fungus. Many of the isolates also reduced the growth rate of the pathogenic fungus. This is very interesting! It is possible that some of these fungi can be used in biological control in the future. We already know that isolates of the species Clonostachys rosea can be used for biological control. But it was a surprise that so many closely related species also have that potential, says Magnus.