Root Herbivory: Grass Species, Epichloë Endophytes and Moisture Status Make a Difference

The root-feeding scarab insect Costelytra giveni causes severe damage to pasture ecosystems in New Zealand. Loline alkaloids produced by some Epichloë endophytes deter this insect. In two experiments, tall fescue infected with E. coenophiala, strain AR584, and endophyte-free (Nil) controls were subjected to pulse drought stress (DS) or well-watered conditions (WW). The second experiment also included meadow fescue infected with E. uncinata. After 4–6 weeks exposure to the different conditions, roots were excised and fed to C. giveni larvae for 7 days. Relative root consumption (RC), frass production, and relative weight change (RWC) of larvae were measured and the loline content of roots determined. RC and frass output were higher for larvae feeding on Nil DS tall fescue than WW and reduced by AR584. RWC was also greater on DS than on WW Nil plants but reduced by endophyte only in DS plants. RC, frass output, and RWC of larvae were reduced by endophyte in DS and WW meadow fescue, but the effect was greater for WW plants. Loline alkaloid concentration in roots was significantly higher in DS than WW tall fescue in Experiment I but higher in WW than DS meadow fescue in Experiment II. These experiments have demonstrated that moisture status interacts with endophyte to differentially affect root herbivory in tall fescue and meadow fescue.

Determination of Loline Alkaloids and Mycelial Biomass in Endophyte-Infected Schedonorus pratensis by Near-Infrared Spectroscopy and Chemometrics

Near infrared spectroscopy (NIRS) is an accurate, fast and nondestructive technique whose use in predicting forage quality has become increasingly relevant in recent decades. Epichloë-infected grass varieties are commonly used in areas with high pest pressure due to their better performances compared to endophyte-free varieties. The insect resistance of Epichloë-infected grasses has been associated with four main groups of endophyte secondary metabolites: ergot alkaloids, indole-diterpenes, lolines and peramine. Concentrations of these alkaloids are usually measured with high performance liquid chromatography or gas chromatography analysis, which are accurate methods but relatively expensive and laborious. In this paper, we developed a rapid method based on NIRS to detect and quantify loline alkaloids in wild accessions of Schedonorus pratensis infected with the fungal endophyte Epichloë uncinata. The quantitative NIR equations obtained by modified partial least squares algorithm had coefficients of correlation of 0.90, 0.78, 0.85, 0.90 for N-acetylloline, N-acetylnorloline and N-formylloline and the sum of the three, respectively. The acquired NIR spectra were also used for developing an equation to predict in planta fungal biomass with a coefficient of correlation of 0.75. These results showed that the use of NIRS and chemometrics allows the quantification of loline alkaloids and mycelial biomass in a heterogeneous set of endophyte-infected meadow fescue samples.

The asymmetric total synthesis of (+)-N-acetyl norloline

The asymmetric total synthesis of (+)-N-acetyl norloline, the putative biogenic precursor of all known loline alkaloids, has been achieved in 12 steps from a commercially available compound.

Influence of nitrogen fertilization on growth and loline alkaloid production of meadow fescue (Festuca pratensis) associated with the fungal symbiont Neotyphodium uncinatum

In a field study during two growing seasons in northern Sweden, we assessed meadow fescue (Festuca pratensis Huds.) with and without Neotyphodium uncinatum to determine whether the endophyte affects plant performance regarding tiller and biomass production. In addition, we measured loline alkaloids produced in infected grasses. Approximately 1000 plants grew at two different levels of nitrogen fertilization: the normal amount applied in this region and one-half that amount. Increasing the amount of nitrogen increased the total number of tillers on the plants. Endophyte-infected plants produced more tillers per plant than plants without the endophyte; there was, however, no significant difference in proportion of reproductive tillers, winter survival, or total biomass production between endophyte-infected and noninfected plants. Infected plants produced loline alkaloids in different quantities without indication of being influenced by different nitrogen fertilization levels.