From Rhizobox to Field Scale: Influence of Tall Fescue Cultivar and Endophyte Status On Rhizosphere Processes.

From Rhizobox to Field Scale: Influence of Tall Fescue Cultivar and Endophyte Status On Rhizosphere Processes Tall fescue (Lolium arundinaceum (Schreb.) is a cool-season perennial grass within which lives a fungal endophyte (Neotyphodium coenophialum) thought to provide tall fescue with a greater competitive ability compared to its non-infected neighbors. Because of the negative consequences of this associated with respect to animal health, lots of researches has been focused on elucidating the chemical components (i.e. alkaloids) produced by Neotyphodium coenophialum, with very little attention paid to the influence the relationship has on rhizosphere processes. Our objective, therefore, is to study the influence of this relationship on root exudates composition and plant biomass. Specifically, we grew two different tall fescue cultivars (PDF and 97TF1) under sterile conditions each without an endophyte (E-), with the common toxic endophyte (E+) and with the novel endophytes AR542 and AR584. After 3 weeks of growth root and shoot biomass of the plants was determined and a portion of the exudates analyzed for total organic carbon and total phenolic content. Another portion of the exudates were analyzed using GC-TOF MS to determine the chemical composition. Preliminary results showed that root biomass in PDF grasses are higher than 97TF1 grasses in all combinations. The root and shoot ratio in novel endophyte infected tall fescue are higher than endophyte free tall fescue. Total phenolic content in common toxic endophyte infected tall fescue is the highest. Based on GC-TOF data, tall fescue exuded organic acids, carbohydrates and fatty acids during their growth period. These results suggested that tall fescue cultivar and endophyte genotype do have an influence on plant biomass and rhizosphere chemical processes. Further research is underway to elucidate how tall fescue cultivar and endophyte genotype affect soil microbial community structure and function via rhizobox study and field soil collection.