Growth and water status in meadow fescue is affected by Neotyphodium and Phialophora species endophytes

Growth and water status in meadow fescue (Festuca elatior L.; syn. F. pratensis Huds.) is affected by Neotyphodium and Phialophora endophytes. Meadow fescue is often infected with Neotyphodium uncinatum (Gams, Petrini & Schmidt) Glenn, Bacon, Price & Hanlin or cosymbiotically with this and a Phialophora-like endophyte. In a growth chamber experiment, we determined the influence of these endophytes on selected growth attributes and plant water status of one genotype of meadow fescue. Single plants of clone M1 free of endophytes (E-) or infected with N. uncinatum (N), Phialophora-like endophyte (P), or both endophytes (NP) were adequately irrigated (control plants) or subjected to a gradually established soil water deficit for 26 d (stressed plants). Afterwards, stressed plants were rewatered and allowed to regrow for 4 wk. Cumulative herbage dry matter (DM) yield was greater in P plants hy 7.5% compared with N plants, generally, Control P plants produced more root DM than E-and NP plants. Root DM in N plants was significantly greater during recovery from drought, compared with P and NP plants (36%). Tiller number of NP plants was the lowest among endophyte treatments in the predrought period. In response to water stress, P plants produced more tillers than E-plants (24%), but average tiller weight of P plants was lower than in E-plants (14%). During imposed water stress, stomatal conductance (g(s)) and leaf water potential (psi(L)) decreased in all plant-endophyte associations to a similar extent. At severe soil water deficit, however, N plants had significantly lower g, and psi(L) than the other plant-endophyte associations. Control plants benefited from the symbiosis with endophytes by increasing: root growth (both endophytes) and shoot growth (Phialophora-like endophyte). Plants infected with N. uncinatum were potentially able to adjust to soil water depletion earlier, suggesting a greater potential for adaptation to drought.