| Fungal endophytes in the genus Neotyphodium infect a wide range of cool season grasses. Neotyphodium is a maternally inherited, obligate symbiont that reproduces asexually by growing into its host's seeds. Because the fitness of Neotyphodium and its host grass are linked, the interaction between host and endophyte is usually predicted to be mutualistic. But in many grass species, like Festuca arizonica (Arizona fescue), Neotyphodium has little or no effect on its hosts. The lack of benefits to hosts, however, does not appear to affect the prevalence of Neotyphodium , as it is common in most native grasses.; Recent studies have shown that Neotyphodium infection confers drought tolerance to its host plant. Neotyphodium infection's influenced on the biomass production and growth of Arizona fescue by growing potted infected (E+) and uninfected (E-) plants under a high (HW) and a low water (LW) availability regime was assessed. Results showed that Neotyphodium infection appears to be beneficial to Arizona fescue performance under LW and detrimental under HW.; The affects of host plant genotype, Neotyphodium infection, water and nutrient availability was assessed on growth and biomass production, gas exchange, and carbon and nitrogen isotopes of four maternal genotypes of Arizona fescue in a long term field study. Evidence suggests that E+ plants should perform better than E- plants under drought. More efficient use of water postpones the decrease in plant water status. This ability to postpone the decrease in plant water status especially may give E+ plants a competitive advantage over E- plants in long periods of drought.; Enhanced competitive abilities have been documented for Neotyphodium infected agronomic grass Festuca arundinacea, Lolium perenne , and Festuca pratensis and these abilities are more pronounced when water availability and nutrient availability are low. Contrary to expectations, Neotyphodium infection did not enhance competitive abilities of Arizona fescue with respects to uninfected conspecifics.; The affect of endophyte haplotype, plant host genotype, endophyte infection, and water availability on traditional growth analysis parameters, in combination with leaf net photosynthesis and dark respiration, conductance to water vapor, water potential, leaf rolling, and stomatal density were measured in four maternal plant genotypes to provide explanations for differences in biomass production and relative growth rates. Our general findings show that Neotyphodium haplotype, Neotyphodium infection, host plant genotype, and environmental conditions influence Arizona fescue physiology, growth, and biomass production and therefore it is also likely that these factors may influence herbivory, inter- and intraspecific competition, and community structure. |
