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The influence of the ectomycorrhizal fungus Rhizopogon subareolatus on growth and nutrient element localisation in two varieties of Douglas fir (Pseudotsuga menziesii var. menziesii and var. glauca) in response to manganese stress.

Ducić T, Parladé J, Polle A - Mycorrhiza (2008)

Bottom Line: Colonisation with R. subareolatus slightly suppressed DFM growth but strongly reduced that of DFG (-50%) despite positive effects of mycorrhizas on plant phosphorus nutrition.Accumulation of high Mn was not prevented in inoculated seedlings.The hyphal mantle of mycorrhizal root tips accumulated divalent cations such as Ca, but not Mn, thus not providing a barrier against excessive Mn uptake into the plants associated with R. subareolatus.

View Article: PubMed Central - PubMed

Affiliation: Institut für Forstbotanik, Georg-August Universität Göttingen, Büsgenweg 2, 37077, Göttingen, Germany.

ABSTRACT
Acidification of forest ecosystems leads to increased plant availability of the micronutrient manganese (Mn), which is toxic when taken up in excess. To investigate whether ectomycorrhizas protect against excessive Mn by improving plant growth and nutrition or by retention of excess Mn in the hyphal mantle, seedlings of two populations of Douglas fir (Pseudotsuga menziesii), two varieties, one being menziesii (DFM) and the other being glauca (DFG), were inoculated with the ectomycorrhizal fungus Rhizopogon subareolatus in sand cultures. Five months after inoculation, half of the inoculated and non-inoculated seedlings were exposed to excess Mn in the nutrient solution for further 5 months. At the end of this period, plant productivity, nutrient concentrations, Mn uptake and subcellular compartmentalisation were evaluated. Non-inoculated, non-stressed DFM plants produced about 2.5 times more biomass than similarly treated DFG. Excess Mn in the nutrient solution led to high accumulation of Mn in needles and roots but only to marginal loss in biomass. Colonisation with R. subareolatus slightly suppressed DFM growth but strongly reduced that of DFG (-50%) despite positive effects of mycorrhizas on plant phosphorus nutrition. Growth reductions of inoculated Douglas fir seedlings were unexpected since the degree of mycorrhization was not high, i.e. ca. 30% in DFM and 8% in DFG. Accumulation of high Mn was not prevented in inoculated seedlings. The hyphal mantle of mycorrhizal root tips accumulated divalent cations such as Ca, but not Mn, thus not providing a barrier against excessive Mn uptake into the plants associated with R. subareolatus.

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Typical mycorrhizal morphotype found on both varieties of Douglas fir seedlings (P. menziesii) var. glauca and var. menziesii (a). Cross section of a mycorrhizal root tip of Douglas fir with R. subareolatus (b). HM Hyphae mantel, HN Hartig net, E epidermis cell, C cortex cell, CC central cylinder. Bar indicates 0.1 mm
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Fig2: Typical mycorrhizal morphotype found on both varieties of Douglas fir seedlings (P. menziesii) var. glauca and var. menziesii (a). Cross section of a mycorrhizal root tip of Douglas fir with R. subareolatus (b). HM Hyphae mantel, HN Hartig net, E epidermis cell, C cortex cell, CC central cylinder. Bar indicates 0.1 mm

Mentions: We suspected that high degrees of mycorrhization might have resulted in large carbon sinks, thereby affecting growth of the two Douglas varieties. In contrast to this assumption, analysis of mycorrhization rates showed that DFM, the variety with higher biomass production, exhibited significantly higher percentage of mycorrhizal colonisation of root tips than DFG (Table 2). Non-inoculated plants also showed low colonisation with ectomycorrhiza, indicating that unintended spreading of ectomycorrhiza was not completely avoided during long-term maintenance in sand culture (Table 2). Only one mycorrhizal morphotype was found on Douglas roots of all experimental treatments (Fig. 2a) and was classified as Rhizopogon sp. (Molina and Trappe 1994; Parladé et al. 1995). Cross sections of mycorrhizal root tips were also examined (Fig. 2b). A typical example, displaying a Hartig net characteristic for vital, functional mycorrhizas, is shown in Fig. 2b. Differences between the varieties or changes of the appearance of the mycorrhizas under the influence of excess Mn were not observed (not shown).Fig. 2


The influence of the ectomycorrhizal fungus Rhizopogon subareolatus on growth and nutrient element localisation in two varieties of Douglas fir (Pseudotsuga menziesii var. menziesii and var. glauca) in response to manganese stress.

Ducić T, Parladé J, Polle A - Mycorrhiza (2008)

Typical mycorrhizal morphotype found on both varieties of Douglas fir seedlings (P. menziesii) var. glauca and var. menziesii (a). Cross section of a mycorrhizal root tip of Douglas fir with R. subareolatus (b). HM Hyphae mantel, HN Hartig net, E epidermis cell, C cortex cell, CC central cylinder. Bar indicates 0.1 mm
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2480516&req=5

Fig2: Typical mycorrhizal morphotype found on both varieties of Douglas fir seedlings (P. menziesii) var. glauca and var. menziesii (a). Cross section of a mycorrhizal root tip of Douglas fir with R. subareolatus (b). HM Hyphae mantel, HN Hartig net, E epidermis cell, C cortex cell, CC central cylinder. Bar indicates 0.1 mm
Mentions: We suspected that high degrees of mycorrhization might have resulted in large carbon sinks, thereby affecting growth of the two Douglas varieties. In contrast to this assumption, analysis of mycorrhization rates showed that DFM, the variety with higher biomass production, exhibited significantly higher percentage of mycorrhizal colonisation of root tips than DFG (Table 2). Non-inoculated plants also showed low colonisation with ectomycorrhiza, indicating that unintended spreading of ectomycorrhiza was not completely avoided during long-term maintenance in sand culture (Table 2). Only one mycorrhizal morphotype was found on Douglas roots of all experimental treatments (Fig. 2a) and was classified as Rhizopogon sp. (Molina and Trappe 1994; Parladé et al. 1995). Cross sections of mycorrhizal root tips were also examined (Fig. 2b). A typical example, displaying a Hartig net characteristic for vital, functional mycorrhizas, is shown in Fig. 2b. Differences between the varieties or changes of the appearance of the mycorrhizas under the influence of excess Mn were not observed (not shown).Fig. 2

Bottom Line: Colonisation with R. subareolatus slightly suppressed DFM growth but strongly reduced that of DFG (-50%) despite positive effects of mycorrhizas on plant phosphorus nutrition.Accumulation of high Mn was not prevented in inoculated seedlings.The hyphal mantle of mycorrhizal root tips accumulated divalent cations such as Ca, but not Mn, thus not providing a barrier against excessive Mn uptake into the plants associated with R. subareolatus.

View Article: PubMed Central - PubMed

Affiliation: Institut für Forstbotanik, Georg-August Universität Göttingen, Büsgenweg 2, 37077, Göttingen, Germany.

ABSTRACT
Acidification of forest ecosystems leads to increased plant availability of the micronutrient manganese (Mn), which is toxic when taken up in excess. To investigate whether ectomycorrhizas protect against excessive Mn by improving plant growth and nutrition or by retention of excess Mn in the hyphal mantle, seedlings of two populations of Douglas fir (Pseudotsuga menziesii), two varieties, one being menziesii (DFM) and the other being glauca (DFG), were inoculated with the ectomycorrhizal fungus Rhizopogon subareolatus in sand cultures. Five months after inoculation, half of the inoculated and non-inoculated seedlings were exposed to excess Mn in the nutrient solution for further 5 months. At the end of this period, plant productivity, nutrient concentrations, Mn uptake and subcellular compartmentalisation were evaluated. Non-inoculated, non-stressed DFM plants produced about 2.5 times more biomass than similarly treated DFG. Excess Mn in the nutrient solution led to high accumulation of Mn in needles and roots but only to marginal loss in biomass. Colonisation with R. subareolatus slightly suppressed DFM growth but strongly reduced that of DFG (-50%) despite positive effects of mycorrhizas on plant phosphorus nutrition. Growth reductions of inoculated Douglas fir seedlings were unexpected since the degree of mycorrhization was not high, i.e. ca. 30% in DFM and 8% in DFG. Accumulation of high Mn was not prevented in inoculated seedlings. The hyphal mantle of mycorrhizal root tips accumulated divalent cations such as Ca, but not Mn, thus not providing a barrier against excessive Mn uptake into the plants associated with R. subareolatus.

Show MeSH
Related in: MedlinePlus