Neotyphodium coenophialum

Neotyphodium coenophialum is a systemic and seed-transmissible symbiont (endophyte) of Lolium arundinaceum (=Festuca arundinacea; tall fescue), a grass endemic to Eurasia and North Africa, but widely naturalized in North America, Australia and New Zealand / Aotearoa. The endophyte has been identified as the cause of the "fescue toxicosis" syndrome sometimes suffered by livestock that graze the N. coenophialum-infected grass. Possible symptoms include poor weight gain, elevated body temperature, reduced conception rates, agalactia, rough hair coat, fat necrosis, loss of switch and ear tips, and lameness or dry gangrene of the feet. Because of the resemblance to symptoms of ergotism in humans, the most likely agents responsible for fescue toxicosis are thought to be the ergot alkaloids produced by N. coenophialum. ^[1]

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Continued popularity of tall fescue with this endophyte, despite episodic livestock toxicosis, is attributable to the exceptional productivity and stress tolerance of the grass in pastures and hay fields. The endophyte enhances several of these characteristics, including drought tolerance, nitrogen utilization, phosphate acquisition, and resistance to nematodes.^[2][3] Recently, natural strains of N. coenophialum with little or no ergot alkaloid production have been introduced into tall fescue for new cultivar development. These strains are apparently not toxic to livestock,^[4] and also provide some, but not necessarily all, of the benefits attributable to the "common toxic" strains in the older tall fescue cultivars. ^[4][3]

Molecular phylogenetic analysis indicates that N. coenophialum is an interspecific hybrid with three ancestors^[5][6]: Epichloë festucae, Epichloë typhina and an undescribed or extinct Neotyphodium species that also contributed a genome to the hybrid endophyte Neotyphodium occultans, among others.

References

1. ^ Lyons PC, Plattner RD, Bacon CW (1986). "Occurrence of peptide and clavine ergot alkaloids in tall fescue grass". Science 232: 487-489. PMID 3008328.
2. ^ Malinowski DP, Belesky DP (2000). "Adaptations of endophyte-infected cool-season grasses to environmental stresses: Mechanisms of drought and mineral stress tolerance". Crop Sci 40: 923-940.
3. ^ ^{a b} Timper P, Gates RN, Bouton JH (2005). "Response of Pratylenchus spp. in tall fescue infected with different strains of the fungal endophyte Neotyphodium coenophialum". Nematology 7: 105-110.
4. ^ ^{a b} Parish JA, McCann MA, Watson RH, Paiva NN, Hoveland CS, Parks AH, Upchurch BL, Hill NS, Bouton JH (2003). "Use of nonergot alkaloid-producing endophytes for alleviating tall fescue toxicosis in stocker cattle". J Animal Sci 81: 2856-2868.
5. ^ Tsai HF, Liu JS, Staben C, Christensen MJ, Latch GC, Siegel MR, Schardl CL (1994). "Evolutionary diversification of fungal endophytes of tall fescue grass by hybridization with Epichloë species". Proc Natl Acad Sci USA 91: 2542-2546. PMID 8172623.
6. ^ Moon CD, Craven KD, Leuchtmann A, Clement SL, Schardl CL (2004). "Prevalence of interspecific hybrids amongst asexual fungal endophytes of grasses". Molec Ecol 13: 1455-1467. PMID 15140090.