Endophyte infection effects on stomatal conductance, osmotic adjustment and drought recovery of tall fescue

Abstract

SUMMARYPresence of the endophytic fungus Acremonium coenophialum Morgan-Jones and Gams in tall fescue {Festuca arundinacea Schreb.) enhances host persistence in drought-prone environments. However, the physiological mechanism is not well understood. We investigated the influence of endophyte infection and water deficit on osmotic adjustment, stomatal conductance, tiller survival and leaf elongation rate of genotype GA87-122 and cv. Kentucky-31 {KV31) of tall fescue. Plants were grown in a greenhouse in pots containing fine-si!ty topsoil {experiment 1) or sand (experiment 2). In expt 1, endophyte-infected (El) and endophyte-free (EF) isolines of GA87-1 22 were exposed to two drought preconditioning cycles, after which all pots were re-watered and osmotic adjustment determined. Osmotic adjustment was -0-46 and -0-51 MPa in El leaf blades and tiller bases and -0-29 and -0-13 MPa in EF leaf blades and tiller bases, respectively. In expt 2, El and EF GA87-122 and KY31 were exposed to severe drought after two preconditioninjj cycles, then re-waiered. During the second preconditioning drying cycle of KY31, stomatal conductance tended to be lower in El than in EE plants, but the difFerence was significant (P ^ 0-05) only at two sampling times. Shoot tissues osmotically adjusted 017-0-31 MPa more in FJ than in FF plants. Tiller survival and leaf elongation rates were higher (P ^ 0-05) in preconditioned El than in EF plants. Basal-zone osmotic adjustment was correlated with tiller survival rate in GA87-122 and KY31 {r = 0-87, F ^ O' Ol for both). Enhanced osmotic adjustment in the meristematic and growing zone might account for improved survival of tillers by facilitating protection of the apical meristem.

Effect of Neotyphodium Uncinatum Endophyte on Meadow Fescue Yielding, Health Status and Ergovaline Production in Host-Plants

“…Most probably the plants infested with N. uncinatum survived the period better due to the symbiont, and thus, there was a higher yield under the conditions enhancing growth, in 2007. The main mechanisms of such an effect of the endophyte are mainly: an increase in the volume of the plant root system, root elongation, earlier and more rapid closing of stomata, accumulation and metabolism of carbohydrates and a greater content of phenolic compounds (Malinowski et al 1997;Elmi and West 1995;Richardson et al 1992). Owing to good growth conditions in 2007, E-plants regenerated and the differences between combinations E+ and E-in 2008, were smaller.…”

Big sacaton and endophyte-infected Arizona fescue germination under water stress

“…These endophytes are vertically-transmitted by hyphae growing into developing seeds (Saikkonen et al 1998). Systemic endophytes may benefit host grasses in several ways, such as by increasing drought tolerance, herbivore resistance, and seed ger-mination (Clay 1987, Latch 1993 Elmi andWest 1995, Schulthess and …”

Enhancement of yield and persistence of perennial ryegrass inoculated with one endophyte isolate in France

“…In tall fescue/Neotyphodium endophyte associations, several mechanisms explain the improved drought tolerance of symbiotic plants such as their enhanced root growth [5], faster leaf-rolling [1], enhanced osmotic adjustment and the maintenance of turgor levels under water stress [14]. The nitrogen deficiency tolerance of symbiotic tall fescue seems to be improved by an increased activity of glutamine synthetase regardless of nitrogen level or form favouring the utilisation of nitrogen [27].…”