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A fungal endophyte vs. the dollar spot pathogen 



Photos by Zipeng Tian

Strong creeping red fescue (Festuca rubra subspecies rubra) plants are often naturally infected with the fungal endophyte Epichloë festucae. Endophyte infection can confer insect and disease resistance to strong creeping red fescue. Endophyte-mediated disease resistance in strong creeping red fescue is not a general feature of other grass-endophyte interactions, and the basis of the disease resistance is currently unknown.

We found that E. festucae from strong creeping red fescue produces an abundant protein similar to a Penicillium antifungal protein. Genes similar to the E. festucae antifungal protein are not found in most Epichloë species for which whole genome sequences are available. The uniqueness of the E. festucae antifungal protein gene and the abundance of the protein indicate that it might be involved in the observed disease resistance of endophyte-infected F. rubra.

In laboratory tests, the antifungal protein inhibited the growth of dollar spot fungus. The antifungal protein may act by damaging the cell membranes of the dollar spot fungus, as evidenced by uptake of Evans blue (see photos), a dye that cannot enter living cells. Treatment of the dollar spot pathogen with the purified antifungal protein allowed the dye to enter the cells, indicating the membranes were damaged. When the dollar spot pathogen was treated with control proteins, the dye was not able to enter the cells.

We have generated a knock-out of the antifungal protein gene and are currently working to assess the effect of the knock-out on dollar spot disease resistance in endophyte-infected turf.

— Zipeng Tian, Ruying Wang, Bruce B. Clarke, Ph.D., and Faith C. Belanger, Ph.D., Rutgers University, New Brunswick, N.J.

Editor’s note: Earlier versions of these summaries were published in the 2016 ASA-CSSA-SSSA Meeting Abstracts, ASA, CSSA and SSSA, Madison, Wis.

Teresa Carson is GCM’s science editor.