Inhibitory effect of earthworm coelomic fluid on growth of the plant parasitic fungus Fusarium oxysporum

Abstract

Interactions between soil biota communities play an important role as intrinsic factors of suppression and degradation of different phytopathogenic soil fungi. There is significant evidence that earthworms can directly affect fungal populations by feeding or by dispersing fungal propagules. Possible effects of indirect contact by secretion of mucus and coelomic fluid were not assessed previously. In the present laboratory study the effects of earthworms' coelomic fluid extract on the growth of Fusarium oxysporum, a phytopathogenic fungi species important in agricultural production, were assessed. The results showed that extracts of coelomic fluid of both tested earthworm species (Dendrobaena veneta and Eisenia fetida) have negative effects on fungal growth. After 48 h, a significant growth reduction was observed in groups treated with extracts containing 2250, 4000 and 4500 coelomocytes/mL. Growth reduction was even more pronounced 72 h after the treatment. The obtained results indicate the possibility that earthworms can affect soil fungi not only by ingestion, but also by contact interaction. This study proved that earthworm coelomic fluid extract shows antifungal activity in in vitro testing. For better understanding of the exact mechanism, studies with soil as a substrate are required, as well as in depth investigation of contact interactions between earthworms and fungi.