Influence of Endophyte and Water Regime Upon Tall Fescue Accessions. II. Pyrrolizidine and Ergopeptine Alkaloids

This is the authors' abstract. We don't add key points for this paper.

Alkaloids, along with specific environmental conditions, have been associated with both detrimental and beneficial aspects of endophyte (Acremonium coenophialum Morgan-Jones et Gams) infected tall fescue (Festuca arundinacea Schreb.) associations. Benefits to the plant accrue through reduced herbivory, whereas detriment to the animal occurs as altered grazing behaviour and reduced productivity. A controlled environment study was conducted to examine pyrrolizidine and ergopeptine alkaloid concentration of four tall fescue accessions as influenced by endophyte status and water regime. Endophyte-free plants were devoid of ergopeptine alkaloid and contained little, if any, pyrrolizidine alkaloid. Leaf blade tissue of endophyte-infected isolines contained a range of both ergopeptine (256 to 1633 ng g−1) and pyrrolizidine (92 to 450 μg g−1) alkaloid concentrations. Water deficit generally increased alkaloid concentration. Alkaloid yield, based upon concentration and tissue d. wt, showed that significant increase in ergopeptine and pyrrolizidine alkaloid in leaf tissue was associated with water deficit and was due to actual increased synthesis and not simply decreased phytomass. Leaf and pseudostem (leaf sheath and stem base) tissue alkaloid concentrations indicated different accumulation patterns for ergopeptine and pyrrolizidine alkaloids. Ergopeptine alkaloid yield increased in water-stressed pseudostem, whereas pyrrolizidine alkaloid yield decreased in some, but not all accessions. The range of host genotype/endophyte biotype response offers the possibility to select associations which produce few deleterious effects in animals yet maintain high forage productivity and persistence.