Bad fungi gone good: how to control Fusarium wilt disease with Fusarium endophytes

Fusarium oxysporum (Fo) is known to cause vascular wilt disease in over 100 different hosts. Although most studies focus on its ability to cause disease, Fusarium is also capable of colonizing plants without triggering disease symptoms. Among these non-pathogenic strains, the endophytic strain Fo47 strain has repetitively been shown to confer protection against wilt disease on tomato caused by Fo f.sp. lycopersici (Fol).

In order to assess how widespread, the capacity is to suppress Fusarium wilt disease, we have acquired a collection of 80 Fo strains isolated from non-cultivated soil or non-symptomatic plants in three different continents (America, Australia and Europe). We found that all the strains tested have the ability to protect to varying degrees against Fusarium wilt disease in tomato in 1:1 co-inoculation assays. Heat killed spores of the biocontrol strain shows no disease suppression. Moreover, we found that pathogen abundance is reduced in the presence of Fo47 in root and stem tissue. Surprisingly, the colonization of Fo47 is increased in tomato stems when co-inoculated with Fol. The plant hormones jasmonic acid, salicylic acid and ethylene do not appear to be required for Fo47-induced suppression of disease. Understanding the mechanisms behind diseases suppression may help us to increase compatibility with Fo endophytic strains and resistance to Fusarium wilt.