Tall Fescue (Festuca arundinacea)

Tall fescue is a cool-season perennial grass that is commonly used for pasture in north Georgia. Tall fescue can also be productive in the Coastal Plain under irrigiation and managed grazing. Fescue grass is most productive during fall through spring, and does not usually grow well in mid-summer.

The majority of tall fescue grown as pasture in Georgia is infected with the endophyte Epichloë coenophialum. This endophyte has a symbiotic relationship with tall fescue in that it imparts positive characteristics in its tall fescue host plant (improves pest resistance, drought tolerance, persistence under grazing, etc.), however livestock that consume endophyte-infected grasses are subject to developing a condition known as fescue toxicosis.

While endophyte-free varieties of tall fescue are available on the market, they are not recommended for use in Georgia due to their decreased persistence in Georgia’s growing conditions. A more recent type of tall fescue on the market is “novel” endophyte-infected tall fescue. These varieties are infected with a strain of the endophyte that confers all the positive characteristics of the wild-type endophyte, but without producing the ergot alkaloids linked to toxicity in livestock. Novel endophyte tall fescue is recommended by UGA economists and forage specialists for use in forage-based livestock systems in Georgia.

Our lab is currently working to develop a novel endophyte variety of tall fescue that is adapted for use in Georgia. By investigating the mechanisms of Epichloë endophytes and simultaneously working towards breeding hardier tall fescue, we hope to be able to combine the two to create a superior cultivar of non-toxic tall fescue for livestock producers statewide.

Endophyte association in cool-season grasses

Genetic-based solutions to endophyte toxicity

Figure 1. PCR products of Jesup tall fescue. Band present around ~1000bp indicates endophyte presence
Figure 2. Immunoblot nictrocellulose membrane with positive and negative controls indicating presence/absence of endophyte

Producers of endophyte-infected tall fescue must have endophyte infection in at least 70% of their seed. In order to effectively screen forage cultivars for endophyte levels, endophyte detection is performed using immunochemical and molecular techniques becaue of their speed and reliability. We have designed PCR markers that can be used to detect endophyte presence in grass seedlings, and validated their efficacy in both tall fescue and perennial ryegrass.

Lee, Kendall & Hill, Nicholas & Dela Cerna, Chloe & Missaoui, A.. (2023). Determining the earliest growth stage to detect the presence of endophytes in tall fescue and perennial ryegrass seedlings using molecular markers. Grassland Research. 2. 10.1002/glr2.12053.

Vertical transmission in artificially infected tall fescue

Figure 3. Image of the sliced meristematic region of a tall fescue seedling prepared for inoculation.
Figure 4. Asexual lifecycle of Epichloe.
Caradus, J.R.; Card, S.D.; Hewitt, K.G.; Hume, D.E.; Johnson, L.J. Asexual Epichloë Fungi—Obligate Mutualists. Encyclopedia 20211, 1084-1100. https://doi.org/10.3390/encyclopedia1040083

The endophyte that is known to commonly infect tall fescue, Epichloë coenophiala, is asexual and vertically transmitted via seed. To better understand endophyte seed transmission for improved forage breeding, we screened several endophyte strains and identified five strains with acceptable compatibility and transmission in tall fescue with both a Continental and Mediterranean background.

Lee, Kendall & Bogdanova, Ana & Missaoui, A.. (2023). Host Genetic Background Effect on Vertical Seed Transmission of Epichloë Endophyte Strains in Tall Fescue. Microbial Ecology. 86. 1-9. 10.1007/s00248-023-02270-2.

Ongoing projects:

Genetic diversity in Festuca spp.

The two types of tall fescue are Continental tall fescue and Mediterranean tall fescue. Continental tall fescue is what is primarily grown in pastures across the United States, but Mediterranean varieties are growing in hot and dry climates.

By utilizing whole-genome sequencing of various accessions of Festuca species with various backgrounds, we aim to bolster our fescue breeding efforts by identifying the genetic mechanisms controlling specific climate-based traits in Mediterranean and Continental genotypes, such as dormancy, drought tolerance, cold survival, etc.

Metabolomic profiling of Epichloë coenophiala endophytes

Epichloe endophytes produce a variety of secondary metabolites. Of these metabolites, some are toxic to mammals, causing ergot toxicosis in livestock; while others are toxic to herbivory insects. By using high performance liquid chromatography-mass spectometry (HP LC-MS), we hope to analyze the alkaloid composition of several Epichloe strains to identify a non-toxic strain that can be successfully utilized in tall fescue.

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