Relationships between the genetic distance of Epichloë festucae isolates and the ergovaline and peramine contents of their Festuca rubra hosts

Abstract

In semiarid grasslands of western Spain, plants of Festuca rubra are frequently infected by Epichloë festucae, an endophyte capable of producing the alkaloids ergovaline, toxic to mammals, and peramine, toxic to insects. The objectives of this paper were to estimate the variability in the content of ergovaline and peramine in plants of Festuca rubra from natural populations and to determine the relationship between the genetic distance among Epichloë strains and the alkaloid contents of plants infected by them. The results showed that a significant variation exits in the ergovaline and peramine contents of infected F. rubra plants, and that variation patterns are different for each alkaloid. Ergovaline content showed a significant variation between years. In contrast, most variation observed in the concentration of peramine occurred between populations. Mantel tests, constrained correspondence analysis (CCA) and generalised analysis of molecular variance (GAMOVA) all revealed a significant relationship between the genetic distances among 35 Epichloë isolates, and the differences in peramine content of their host plants. The relationship observed for ergovaline was more ambiguous. This indicates that plants infected by genetically close isolates of Epichloë festucae tend to be similar in terms of peramine content, while the ergovaline content of infected plants seems to be more dependent on external factors. The results of this study suggest that the selection of Epichloë festucae endophytes based on the alkaloid content of their host plants can be a successful strategy to select good or bad producers of peramine, but may not be a reliable method to detect fungal strains associated with particular ergovaline production profiles.