The Role of Endophytic Fungi Isolated from Native Iranian Yew (Taxus baccata) in Biological Control of Fusarium oxysporum

The yew tree is a native conifer of Iran. This plant is the main source of the anti-cancer drug Taxol. Research has shown that yew coexisted with endogenous fungi. These endophytes increase food availability, resistance to pests, diseases, and environmental stresses by producing secondary metabolites that they provide to their hosts. Isolation and characterization of this type of microorganism can be important to discover new species with the potential to produce antimicrobial compounds. Therefore, this study was performed to investigate the effect of systemic fungicides and antagonistic effects of endophytic fungi isolated from yew against the pathogenic fungus Fusarium oxysporum.

This research was conducted in Gorgan University of Agricultural Sciences and Natural Resources. To isolate the endophytes, two groups of plants were used, including plants treated with systemic fungicides (Rovral-TS and Fosetyl aluminum) and control. Treatments were applied by foliar application in three periods with an interval of seven days. After foliar application, the root, stem, and leaf of experimental plants were used to isolate endophytes. Selected isolated endophytes were used to determine the percentage of inhibition against F. oxysporum. Finally, molecular identification of selected and effective strains from isolated endophytic fungi was performed.

The research results showed that all the endophytic fungi isolated from yew could inhibit pathogen growth. Based on molecular studies, five strains of identified endophytic fungi belonged to the genera Fusarium, Phomopsis, and Colletotrichum. Fungi which were identified from fosetyl aluminum-treated organs showed the most growth inhibitory effect. Among the identified fungi, Fusarium solani had the highest inhibitory power with 71.81% inhibition, which was obtained from yew seedlings treated with rovral-TS systemic fungicide. The least inhibitory effect was related to Phomopsis sp. with 12.97% inhibition. This fungus was isolated from yew seedlings in the control treatment.

In general, the results showed that endophytic fungi isolated from native Iranian yew seedlings have a high ability to biologically control the pathogen F. oxysporum. In addition, the application of systemic fungicides not only directly inhibits pathogens, but strengthening endophytic fungi can protect the plant against pathogens as well.