Incidence and Distribution of the Tall Fescue Endophyte in the United States

Shelby, Richard A.; Dalrymple, Lisa

doi:10.1094/pd-71-0783

Cited by 116 publications

(42 citation statements)

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“…The 30 yr average maximum temperature for July in the 13 state Southeastern Region is 33 °C (U.S. Bureau of the Census, 1992). A study of fungal-endophyte infection frequencies in tall fescue in the U.S..A., suggested that infected plants might be more common in southern states with higher average temperatures (Shelby & Dalrymple, 1987). However, there was a great deal of heterogeneity in infection frequencies among states which could have resulted from differences in infection rates of germinating seeds as well as differences in long-term survival and reproduction of infected and uninfected plants.…”

Section: Discussionmentioning

confidence: 99%

Physiological responses of Festuca arundinacea to fungal endophyte infection

1996

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SUMMARYEnhanced growth rates of several grass species infected by fungal endophytes are known, hut the underlying changes in plant physiology are not. Carbon exchange rates (CER) and leaf conductances {g) of 13 genotypes of tall fescue {Festuca arundinacea Schreb. var. KY 31) infected by the fungal endophyte Acremonimn coenophialum Morgan-Jones and Gams were measured at ambient conditions. Endophyte-free ramets of the same genotypes were also measured. Correlations were calculated hetween environmental conditions at the time of measurement, and physiological responses. The only differential response of infected and uninfected ramets was to temperature. At low leaf temperatures no difference was seen between infected and uninfected plants. However, at leaf temperatures above 35 °C infected tall fescue plants photosynthesized at a significantly greater rate (20-25 %) than uninfected plants. This resulted from a decrease in the CER of uninfected plants, not an increase in the rate of infected plants, at high temperature. There were also significant infection x genotype interactions, indicating that the response to infection was specific to a given genotype. These results indicate that physiological responses of host plants to fungal endophyte infection depend both on the physical environment and the genotype of the plants.

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Section: Discussionmentioning

confidence: 99%

Physiological responses of Festuca arundinacea to fungal endophyte infection

1996

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“…However, we could isolate the fungus from seeds and detect hyphae in the embryo indicating that vertical transmission occurs. In other grasses, such as F. arundinacea and L. perenne, vertical transmission is sometimes imperfect, leaving some of the progeny of infected plants uninfected (Hinton & Bacon, 1985 ;Welty et al, 1994 ;Ravel et al, 1997 (Shelby & Dalrymple, 1987 ;Cunningham et al, 1993).…”

Section: Infection Levelmentioning

confidence: 99%

Multistrain infections of the grass Brachypodium sylvaticum by its fungal endophyte Epichloë sylvatica

Meijer

Leuchtmann

1999

New Phytologist

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Endophytes of the genus EpichloeW (Clavicipitaceae, Ascomycota) are systemic symbionts of cool-season grasses. Their interactions with grass hosts may vary between mutualistic and pathogenic depending on the mode of endophyte reproduction. Sexual strains prevent flowering and seed set (choke disease) of the host and can be horizontally transmitted by ascospores, while asexual strains remain asymptomatic and are vertically transmitted through seeds. In Switzerland nearly all plants of Brachypodium sylvaticum (Huds.) P.B. are infected by EpichloeW sylvatica Leuchtmann & Schardl, but choke symptoms are formed very rarely, and are restricted to particular locations and to a minority of plants at those locations. Earlier research has revealed that E. sylvatica is genetically differentiated into sexual and asexual subpopulations. Given the high level of infection and assuming horizontal transmission of sexual strains, multiple host infections have been predicted. In this study, 25 plants out of 63 examined by isozyme analysis were found to be infected by two or three different endophyte genotypes. In most cases endophyte genotypes appeared to be correlated with the symptom type of a particular tiller, suggesting that the fungal genome controls choke formation and that the sexual and asexual subpopulations are separated at the ramet (tiller) level rather than at the genet (plant) level. These conclusions were further supported by analyses with log-linear models of the population structure of E. sylvatica at four locations where choke symptoms were present. These analyses also revealed a geographic structure in the asexual subpopulation but not in the sexual subpopulation which could be caused by the different dispersal ranges of their propagules. The rare occurrence of sexually reproducing strains and the dominance of a single genotype in asymptomatic plant populations may be explained by the colonization history of B. sylvaticum and its endophyte in Switzerland.

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“…However, endophyte-free sites and sites with low levels of infection (Ͻ25%) exist also. For example, in the United States, where tall fescue is introduced, 58% of 1,483 samples from 26 states were infected by the endophyte (35). In Kentucky, 97% of 200 fields spanning 42 counties were infected, with mean infection frequencies varying 67-100% (36).…”

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Herbivores cause a rapid increase in hereditary symbiosis and alter plant community composition

Clay

Holah

Rudgers

2005

Proc. Natl. Acad. Sci. U.S.A.

182

187

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Microbial symbioses are ubiquitous in nature. Hereditary symbionts warrant particular attention because of their direct effects on the evolutionary potential of their hosts. In plants, hereditary fungal endophytes can increase the competitive ability, drought tolerance, and herbivore resistance of their host, although it is unclear whether or how these ecological benefits may alter the dynamics of the endophyte symbiosis over time. Here, we demonstrate that herbivores alter the dynamics of a hereditary symbiont under field conditions. Also, we show that changes in symbiont frequency were accompanied by shifts in the overall structure of the plant community. Replicated 25-m 2 plots were enriched with seed of the introduced grass, Lolium arundinaceum at an initial frequency of 50% infection by the systemic, seedtransmitted endophyte Neotyphodium coenophialum. Over 54 months, there was a significantly greater increase in endophyteinfection frequency in the presence of herbivores (30% increase) than where mammalian and insect herbivory were experimentally reduced by fencing and insecticide application (12% increase). Under ambient mammalian herbivory, the above-ground biomass of nonhost plant species was reduced compared with the mammalexclusion treatment, and plant composition shifted toward greater relative biomass of infected, tall fescue grass. These results demonstrate that herbivores can drive plant-microbe dynamics and, in doing so, modify plant community structure directly and indirectly.dynamics ͉ grasslands ͉ herbivory ͉ endophyte

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Incidence and Distribution of the Tall Fescue Endophyte in the United States

Cited by 116 publications

References 0 publications

Physiological responses of Festuca arundinacea to fungal endophyte infection

Physiological responses of Festuca arundinacea to fungal endophyte infection

Multistrain infections of the grass Brachypodium sylvaticum by its fungal endophyte Epichloë sylvatica

Herbivores cause a rapid increase in hereditary symbiosis and alter plant community composition

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