Gene flow in the endophyte Neotyphodium and implications for coevolution with Festuca arizonica

Area of Science:

• Plant-microbe interactions
• Mycology
• Population genetics

Background:

• Arizona fescue (Festuca arizonica) commonly hosts asymptomatic Neotyphodium endophytes.
• In cultivated grasses, Neotyphodium endophytes confer mutualistic benefits via alkaloid production for herbivore deterrence.
• Neotyphodium in Arizona fescue typically produces low alkaloid levels, suggesting a non-mutualistic relationship.

Purpose of the Study:

• To investigate gene flow rates among Neotyphodium populations in Arizona fescue.
• To understand the genetic diversity and potential hybridization events within Neotyphodium endophytes.
• To explore the implications of gene flow on endophyte-host interactions and alkaloid production.

Main Methods:

• Utilized microsatellite markers to analyze Neotyphodium populations across four Arizona sites.
• Assessed haplotypic diversity and identified potential instances of vegetative hybridization.
• Compared Neotyphodium gene flow rates with host (Festuca arizonica) pollen-mediated gene flow.

Main Results:

• Observed generally low haplotypic diversity within Neotyphodium populations.
• Detected evidence of vegetative hybridization between Neotyphodium and Epichloë species.
• Found significantly low gene flow among Neotyphodium populations, much lower than that of the host grass.

Conclusions:

• Limited Neotyphodium gene flow, contrasted with host gene flow, can lead to trait mismatching.
• This mismatch likely contributes to the reduced or absent alkaloid production in Neotyphodium of Arizona fescue.
• Findings offer insights into the evolution of endophyte-host dynamics in native grass systems.