Epichloë

Litter decomposition is a key ecosystem process which returns nutrients from dead plant material to mineral forms in the soil. We examined whether systemic fungal endophytes modulate recycling of nutrients directly by altering litter decomposition. We studied litter decomposition mediated by Epichlo€ e endophytes in litter-bag experiments. We examined direct endophyte effects on litter decomposition in wild populations and cultivars of Schedonorus phoenix and Schedonorus pratensis. In the first experiment, endophyte presence tended to increase litter decomposition rate in cultivars of the two grass species (S. phoenix and S. pratensis). However, in the second experiment plant origin had a stronger influence than endophyte symbiosis in S. phoenix. Interestingly, the initial level of alkaloids was associated positively with decomposition in S. phoenix populations. Characteristics associated with litter quality were not clearly related to either endophytes or decomposition rate. Our results suggest that endophytes can enhance litter breakdown but their role in nutrient cycling is far more complex depending on plant population origin.

Asexual Epichloë endophytes are prevalent in cool season grasses, and many are of hybrid origin. Hybridization of asexual endophytes is thought to provide a rapid influx of genetic variation that may be adaptive to endophyte-host grass symbiota in stressful environments. For Arizona fescue (Festuca arizonica), hybrid symbiota are commonly found in resource-poor environments, whereas non-hybrid symbiota are more common in resource-rich environments. There have been very few experimental tests where infection, hybrid and non-hybrid status, and plant genotype have been controlled to tease apart their effects on host phenotype and fitness in different environments. We conducted a greenhouse experiment where hybrid (H) and non-hybrid (NH) endophytes were inoculated into plant genotypes that were originally uninfected (E-) or once infected with either the H or NH endophytes. Nine endophyte and plant genotypic group combinations were grown under low and high water and nutrient treatments. ...