Neotyphodium coenophialum‐endophyte infection affects the ability of tall fescue to use sparingly available phosphorus

Abstract

Neotyphodium coenophialum, (Morgan-Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non-infected isolines on phosphorus (P)-deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E-) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg -1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high 1 Corresponding author. 835 836 MALINOWSKI AND BELESKY specificity of endophyte-tall fescue associations. Endophyte infection did not affect root dry matter (DM) when no P was supplied but shoot DM was reduced by 20%. More biomass was produced and greater P uptake rate occurred in PR than PF treatment. Root DM was greater in E+ DN4 than E-DN4 when supplied with either PF or PR. In contrast, endophyte infection did not affect root DM of DN2, regardless of P source. Relative growth rate (RGR) of E+ plants grown with PR was 16% greater than that of E-plants. Endophyte infection did not improve growth or P uptake in PF treatment. When PR was supplied, P uptake rate was 24% greater in E+ DN2 than E-DN2, but endophyte infection did not benefit DN4. Phosphorus-use efficiency was 6% less in E+ DN2 but 16% greater in E+ DN4 compared to E-plants, regardless of P source. Root exudates of E+ DN2, but not E+ DN4 solubilized more P from PR than those of E-plants. The correlation between root RGR and P uptake rate was relatively high for E-plants (r=0.76), but low for E+ plants (r=0.27) grown with PR. Results suggest that P uptake by E+ tall fescue might rely on mechanisms other than an increase in root biomass (surface area). Endophyte infection modified tall fescue responses to P source. This phenomenon was associated with modes of P acquisition which included enhanced activity of root exudates in releasing P from PR in E+ plants (DN2), and increased root biomass (DN4). The dominant means of P acquisition may be determined by a specific association of endophyte and tall fescue genomes. Endophyte-tall fescue association plasticity contributes to widespread success of symbiotic in marginal resource conditions.

Phosphorus solubilization and uptake by dark septate fungi in fourwing saltbush, Atriplex canescens (Pursh) Nutt

“…Additionally, it was shown that P use efficiency was greater in plants accessing P from the RP and TCP treatments compared to plants receiving adequate soluble P directly to their roots in the AAP treatments. Malinowski & Belesky (1999) also found that phosphorus use efficiency was 16% greater in endophyte-infected tall fescue plants than in non-infected plants. This suggests that P use efficiency is greater when P is supplied by the fungus.…”

“…To a lesser extent, shoot and root biomass was greater in RP-treated plants than those receiving no P (0P). Malinowski & Belesky (1999) also found that root dry matter was greater in endophyte-infected tall fescue pastures fertilized with rock phosphate than in pastures fertilized with commercial fertilizer providing plant available P. Microscopic analysis revealed that roots in all treatments were internally colonized by A. ustus. Due to the variability in the nature and composition of internal DS fungal structures many of these structures are not microscopically visible making it impossible to accurately quantify their presence (Barrow & Aaltonen, 2001).…”

Epichloë festucae and Related Mutualistic Symbionts of Grasses

“…Endophyte benefits to their host plants include enhanced drought tolerance (Arechavaleta et al, 1989;Malinowski et al, 1997), resistance to nematodes (Kimmons et al, 1990;West et al, 1988), and growth enhancements (Malinowski and Belesky, 1999). E. festucae was also found to enhance resistance to dollar spot disease caused by Sclerotinia homeocarpa (J. F. White, personal communication).…”

“…Fungal symbionts of the related genera Epichloë (which have a sexual state) and Neotyphodium (strictly asexual) are symbionts of many cool-season grasses (subfamily Pooideae) (Clay and Leuchtmann, 1989;, to which they provide a variety of fitness enhancements such as increased resistance to herbivory, parasitism, and drought, as well as growth enhancements (reviewed in Clay, 1990;Schardl and Clay, 1997) and improved nutrient acquisition (Malinowski and Belesky, 1999). Interest in these fungal "endophytes" at the turn of the 20th century was sparked by observations of toxicoses to animals grazing certain grasses.…”

Screening and Identifying a Cadmium-resistant Fungus and Characterizing its Cadmium Adsorption

“…When more than 20 mL of fermented liquid was added, root biomass was reduced. This might be because high doses of fermented liquid adsorbed much Cd 2+ and reduced Cd 2+ -induced stress in rice root, so the rice foot fully absorb the nutrient elements in the soil, such as phosphorus [35] and nitrogen [36], and delivered them to the above-ground parts of the rice, making them grow rapidly. The synthesis of a large amount of organic matters increases the fresh weight of rice seedlings and finally improved rice growth.…”