Ectomycorrhizal protection of Pinus sylvestris against copper toxicity

Abstract

Summary• Change in the copper (Cu) sensitivity of Pinus sylvestris is presented, in response to the ectomycorrhizal fungi, Suillus bovinus and Thelephora terrestris , common mycobionts on metal contaminated sites.• Seedlings grown under phosphorus (P) limitation were exposed to a range of Cu concentrations. Plant and fungal development, P nutrition, sorption of Cu on roots and external mycelia as well as transfer of Cu to shoots were assessed.• Root growth and P nutrition were severely inhibited in nonmycorrhizal pines at elevated Cu compared with mycorrhizal plants. Excess Cu had little effect on the development of mycorrhizal roots and mycelia. Thelephora terrestris was less sensitive to Cu stress than S. bovinus . The extraradical mycelium of S. bovinus retained large amounts of Cu. However, binding of Cu in fungal tissue was not a prerequisite for low Cu sensitivity since T. terrestris absorbed considerably less Cu that S. bovinus .• Both ectomycorrhizal fungi protect P. sylvestris against Cu toxicity; a benefit that was not due to a metal dilution effect. The mechanisms of mycorrhizal amelioration of Cu toxicity are probably diverse and species-dependent.

Copper-Adapted Suillus luteus , a Symbiotic Solution for Pines Colonizing Cu Mine Spoils

“…At the highest Cu concentration, the Cu/P ratio in NM plants (1.4) was considerably higher than the ratios in mycorrhizal plants (0.4 for the UH-Slu-Fg1.6 isolate and 0.7 for the UH-Slu-Lsk10 isolate), indicating that the fungi are able to maintain a more favorable nutritional status for their pine hosts. In a previous study we found evidence that the ECM fungi S. bovinus and Thelephora terrestris could protect pines from Cu stress (28). In both studies, the ameliorating effect of the ECM fungi on host fitness could be ascribed to better plant nutrition and reduced uptake of Cu.…”

“…Inoculated and noninoculated plants were divided at random into four Cu treatments to create a factorial setup with the factors Cu treatment (0.1, 15, 30, and 60 M Cu 2ϩ ) and fungal inoculation. This Cu gradient was selected because it results in severe disturbance of tree root functioning in (semi-)hydroponic conditions (26,28). For each combined treatment there were five replicates.…”

“…The ergosterol assay is a sensitive method for determining active fungal biomass in mixed plant-fungus tissues exposed to elevated Cu levels (24,28). The ergosterol data were converted to fungal biomass by using a conversion factor of 4.2 mg ergosterol g (dry weight) mycelium Ϫ1 .…”

Role of Microorganisms in Plant Nutrition and Health

“…Mycorrhizal fungi also modify the interactions of plants with other soil organisms, both pathogenic (nematodes and fungi) as well as mutualists (nitrogen-fixing bacteria) (van Tichelen et al 2001). Pathogenic fungi may invade roots but mycorrhizal fungi alter host response to these pathogens.…”

Evaluación del estado micorrícico de plántulas de Pinus ponderosa producidas bajo fertirriego, sin manejo de la micorrización

“…Numerosos estudios han demostrado la superioridad de las plántulas micorrizadas frente a las no micorrizadas en términos de establecimiento y supervivencia en campo, generando mejores respuestas a los crecimientos en las forestaciones (Gagnon et al 1988 y referencias allí incluidas, Stenström et al 1990, Krasowski et al 1999, Jumpponen 2001, Van Tichelen et al 2001, Dunabeitia et al 2004, Ortega et al 2004. Sin embargo, el manejo de la micorrización bajo sistemas que reciben fertilización requiere un estudio detallado para cada caso, dado que existen reportes contradictorios sobre el efecto inhibidor de la fertilización sobre la micorrización, dependiendo de las especies arbóreas y fúngicas involucradas (Menkis et al 2005).…”