The Endophyte Neotyphodium coenophialum Affects Root Morphology of Tall Fescue Grown under Phosphorus Deficiency

Abstract

Mechanisms involved in mineral stress tolerance of cool‐season grasses infected by Neotyphodium spp. endophytes are not known. In a controlled‐environment experiment, two genotypes (DN2 and DN4) of tall fescue (Festuca arundinacea Schreb.) infected (E+) with their naturally occurring strains of N. coenophialum (Morgan‐Jones and Gams) Glenn, Bacon and Hanlin, and their non‐infected (E−) isolines were cultivated in nutrient solution at two phosphorus (P) levels of 31 mg P dm−3 (P+) and 0.31 mg P dm−3 (P−) for 3 weeks. Diameters of lateral roots, root hair length, and distance between root hairs were recorded using a digital image analysis system (Dage 72S CCD camera controlled by a Power MacIntosh 7200/120PC compatible computer equipped with an AG‐5 frame grabber board and NIH‐Image). Irrespective of tall fescue genotype and P level in nutrient solution, E+ plants had roots with a smaller diameter (16 %) than E− plants. In response to P deficiency, root diameter of E+ plants declined by 11 % and root hair length increased by 17 % when compared to E− plants. Altered root diameter and root hair length might be one of the mineral stress tolerance mechanisms in endophyte‐infected tall fescue.

Response of Neotyphodium lolii-infected perennial ryegrass to phosphorus deficiency

“…Similar results were also achieved in tall fescue. In series of reports made by Malinowski et al (1998Malinowski et al ( , 1999aMalinowski et al ( , b, 2000, they found that root DW of specific EI genotype (DN4) was 10% greater than that of EF plants Belesky 1999, 2000); EI plants produced roots with smaller diameters and longer root hairs (Malinowski et al 1998(Malinowski et al , 1999b. Roots are responsible for mineral acquisition.…”

“…Azevedo and Welty (1995) firstly confirmed reduced photosynthesis rates and growth of EI tall fescue at high P availability, and it was also found that high concentrations of inorganic P in endophyte hyphae grows epiphytically on tall fescue roots, similar to that found in mycorrhizal fungi. Malinowski et al (1999b) found that EI tall fescue expressed increased root absorption area through reduced root diameter and increased root hair length when compared with the EF counterpart. The rhizosphere of tall fescue was also chemically modified in response to endophyte infection resulting from the release of phenolic-like compounds from roots (Malinowski et al 1998).…”

Biological properties of Endophytic Fungi

“…Many endophytes are capable of solubilization of phosphate, enhance uptake of phosphorus (P), nitrogen fixation, production of siderophores, and plant hormones such as auxin, abscisins, ethylene, gibberellins, and indole acetic acid (IAA), which are important for plant growth regulations (Goodman et al 1986;Barraquio et al 1997;Malinowski et al 1999;Zou et al 1999;Malinowski and Belesky 2000;Boddey et al 2003;Loiret et al 2004, Sandhiya et al 2005, Firáková et al 2007). Gibberellic acid (GA) is a potent phytohormone, that regulates plant growth.…”

Niche Differentiation in the Dynamics of Host-Symbiont Interactions: Symbiont Prevalence as a Coexistence Problem

“….8). However, other root characteristics, such as rooting depth or root hair length, could affect resource partitioning (Malinowskli et al 1999), or host types could specialize on different forms of nutrients (e.g., McKane et al 2002).…”