Evidence for chemical changes on the root surface of tall fescue in response to infection with the fungal endophyte Neotyphodium coenophialum |
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Authors: | Malinowski Dariusz P Alloush Ghiath A Belesky David P |
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Institution: | (1) Appalachian Soil and Water Conservation Research Laboratory, USDA-ARS, Beaver, West Virginia 25813-9423, USA;(2) Dep. of Soil Science and Plant Nutrition, Tishreen University, Lattakia, Syria |
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Abstract: | Endophyte-infected (E+) tall fescue (Festuca arundinacea Schreb.) plants grown in phosphorus (P) deficient soils accumulate more P in roots and shoots than noninfected isolines. In a growth chamber experiment, four tall fescue genotypes DN2, DN4, DN7, and DN11, infected with their naturally occurring strains of Neotyphodium coenophialum (Morgan-Jones & Gams) Glenn, Bacon & Hanlin, and their noninfected isolines (E-), were cultivated in nutrient solution at two P levels: 31 ppm (P+) and 0 ppm (P-) for 4 wk. The Fe3+ reducing activity of extracellular reductants and intact root tissues, and total phenolic concentration in roots and shoots were measured. Endophyte infection significantly increased Fe3+ reducing activity rate of extracellular reductants (9.6 × 10-3 mol Fe3+ h-1 g-1 root FW) when compared to E- plants (3.9 × 10-3) and Fe3+ reduction rate of intact root tissues (6.16 and 4.48 mol Fe3+ h-1 g-1 root FW, respectively for E+ and E- plants). In response to P deficiency, Fe3+ reduction rate of intact root tissues increased in E+ plants by 375% when compared to E- plants, whereas no significant differences were observed when P was provided. Total phenolic concentration was 20% greater in shoots of E+ plants than in E- plants. In response to P deficiency, total phenolic concentration significantly increased in roots of E+ plants by 7%, and decreased in roots of E- plants by 10%. The most active Fe3+ reducing zones were located along branching of secondary and tertiary roots. The Fe3+ reducing activity on the root surface and total phenolic concentration in roots and shoots increased dramatically in response to endophyte infection, especially under P limiting conditions.Visiting Scientist sponsored by the Fulbright Program No. 21133 |
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Keywords: | endophyte Festuca arundinacea Neotyphodium coenophialum phenolics phosphorus root activity tall fescue |
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