Saikkonen, Kari

Tuomi, Juha

Wäli, Pauliina

Wäli, Piippa

PLoS ONE

PubMed

<div><p>It is well recognized, that outcomes of mutualistic plant-microorganism interactions are often context dependent and can range from mutualistic to antagonistic depending on conditions. Instead, seemingly pathogenic associations are generally considered only harmful to plants. The ergot fungus (<i>Claviceps purpurea</i>) is a common seed pathogen of grasses and cereals. Ergot sclerotia contain alkaloids which can cause severe toxicity in mammals when ingested, and thus the fungal infection might provide protection for the host plant against mammalian herbivores. Theoretically, the net effect of ergot infection would positively affect host seed set if the cost is not too high and the defensive effect is strong enough. According to our empirical data, this situation is plausible. First, we found no statistically significant seed loss in wild red fescue (<i>Festuca rubra</i>) inflorescences due to ergot infection, but the seed succession decreased along increasing number of sclerotia. Second, in a food choice experiment, sheep showed avoidance against forage containing ergot. Third, the frequency of ergot-infected inflorescences was higher in sheep pastures than surrounding ungrazed areas, indicating a protective effect against mammalian grazing. We conclude that, although ergot can primarily be categorized as a plant pathogen, ergot infection may sometimes represent indirect beneficial effects for the host plant. Ergot may thus serve as a conditional defensive mutualist for its host grass, and the pathogenic interaction may range from antagonistic to mutualistic depending on the situation.</p></div

Pauliina P. Wäli (432305)

Piippa R. Wäli (363608)

Kari Saikkonen (363607)

Juha Tuomi (432306)

The Francis Crick Institute

Is the Pathogenic Ergot Fungus a Conditional Defensive Mutualist for Its Host Grass?

Jukuri

Pauliina P. Wäli

Piippa R. Wäli

Kari Saikkonen

Juha Tuomi

Crossref

It is well recognized, that outcomes of mutualistic plant-microorganism interactions are often context dependent and can range from mutualistic to antagonistic depending on conditions. Instead, seemingly pathogenic associations are generally considered only harmful to plants. The ergot fungus (Claviceps purpurea) is a common seed pathogen of grasses and cereals. Ergot sclerotia contain alkaloids which can cause severe toxicity in mammals when ingested, and thus the fungal infection might provide protection for the host plant against mammalian herbivores. Theoretically, the net effect of ergot infection would positively affect host seed set if the cost is not too high and the defensive effect is strong enough. According to our empirical data, this situation is plausible. First, we found no statistically significant seed loss in wild red fescue (Festuca rubra) inflorescences due to ergot infection, but the seed succession decreased along increasing number of sclerotia. Second, in a food choice experiment, sheep showed avoidance against forage containing ergot. Third, the frequency of ergot-infected inflorescences was higher in sheep pastures than surrounding ungrazed areas, indicating a protective effect against mammalian grazing. We conclude that, although ergot can primarily be categorized as a plant pathogen, ergot infection may sometimes represent indirect beneficial effects for the host plant. Ergot may thus serve as a conditional defensive mutualist for its host grass, and the pathogenic interaction may range from antagonistic to mutualistic depending on the situation

Pauliina P Wäli

Piippa R Wäli

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Is the pathogenic ergot fungus a conditional defensive mutualist for its host grass?

Is the Pathogenic Ergot Fungus a Conditional Defensive Mutualist for Its Host Grass?

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The Francis Crick Institute

Jukuri

Crossref

Directory of Open Access Journals