Endophytic Response to Methyl Jasmonate and Loline Quantification
Dr. Thomas Bultman
Tall fescue (Schedonorus phoenix) is a grass found throughout much of the USA and Europe, and is known to harbor the fungal endophyte Neotyphodium coenophialum. The fungus forms a mutualistic relationship with the host, providing both biotic and abiotic stress tolerance and resistance. Often, the highly selected agronomic cultivar kentucky-31 is used for much of the endophytic-host research, as opposed to a naturalized grass. Therefore, seeds were obtained from Gotland, Finland in order to study the effect of a naturalized cultivar of tall fescue and response to application of methyl jasmonate (MJ). Further, it is common for experiments to use mechanically uninfected seeds to act as naturally endophyte-negative seeds. The purpose of the testing naturalized tall fescue expanded further to using naturally uninfected and mechanically uninfected grass seeds. Plants were exposed to MJ by gaseous diffusion within a controlled environmental chamber, and response was assessed with an aphid (R. padi) bioassay. As in Simons et al. (2008), MJ decreased the resistance of endophyte-infected grasses. Further, there was no difference among mechanically uninfected and naturally uninfected treatments, suggesting that both types are viable for experimental use to act as an endophyte-negative treatment. Constitutive production of toxic chemicals to herbivores is one of the key components of herbivore resistance. However, damage to the plant (or perhaps the fungus) induces an increase in alkaloid production. Samples of KY-31 cultivar from a previous damage-treatment experiment were used to quantify loline levels. Data show that loline levels peak when the plant is cut where the fungus resides, suggesting that it is not damage to the host plant that causes an induced increase of protective alkaloids, but rather damage to the endophyte itself.
A recommended citation will become available once a downloadable file has been added to this entry.