Journal Article

Nutrient uptake by intact mycorrhizal <i>Pinus sylvestris</i> seedlings: a diagnostic tool to detect copper toxicity

Katia K. Van Tichelen, Tom Vanstraelen and Jan V. Colpaert

in Tree Physiology

Volume 19, issue 3, pages 189-196
Published in print March 1999 | ISSN: 0829-318X
Published online March 1999 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/19.3.189
Nutrient uptake by intact mycorrhizal Pinus sylvestris seedlings: a diagnostic tool to detect copper toxicity

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We developed a nondestructive method for detecting early toxic effects of inflethal copper (Cu) concentrations on ectomycorrhizal and non-mycorrhizal (NM) Scots pine (Pinus sylvestris L.) seedlings. The fungal symbionts examined were Paxillus involutus (Fr.) Fr., Suillus luteus (Fr.) S.F. Gray and Thelephora terrestris(Ehrh.) Fr. The accumulation of Cu in needles and fungal development (ergosterol) in roots and infstrate were assessed. Inorganic phosphate (Pi) and ammonium (NH4+) uptake capacities were determined in a semi-hydroponic cultivation system on intact P-limited plants that were exposed for 3 weeks to 0.32 (control), 8 or 16 μmoles Cu2+. Short-term effects of a 1-hour exposure to 32 μmoles Cu2+ on nutrient uptake rates were also determined.

None of the Cu2+ treatments affected plant growth or root ergosterol concentrations. The active fungal biomass in infstrate invaded by S. luteus was reduced by 50% in the 16 μM Cu2+ treatment compared with the control treatment; however, colonization by S. luteus prevented an increased accumulation of Cu in the needles. In contrast, the 16 μM Cu2+ treatment caused a 2.2-fold increase in needle Cu concentration in NM plants. Ergosterol concentrations in the infstrate colonized by P. involutus and T. terrestris were not affected by 16 μmolar Cu2+. Although P. involutus and T. terrestris were less sensitive to Cu2+ than S. luteus, T. terrestris did not prevent the accumulation of Cu in needles of its host plant in the 16 μmolar Cu2+ treatment.

Mycorrhizal plants consistently had higher Pi and NH4+ uptake capacities than NM plants. In the control treatment, specific Pi uptake rates were almost 10, 4 and 3 times higher in plants associated with P. involutus, S. luteus and T. terrestris, respectively, than in NM plants, and specific NH4+ uptake rates were about 2, 2 and 5 times higher, respectively, than those of NM seedlings. Compared with the corresponding control plants, a 3-week exposure to 8 μM Cu2+ had no effect on the nutrient uptake potential of plants. In contrast, the 16 μM Cu2+ treatment significantly reduced Pi uptake capacity of all plants and decreased NH4+ uptake capacity of seedlings colonized by S. luteus or T. terrestris. The 32 μM Cu2+ 1-h shock treatment reduced specific NH4+ and Pi uptake rates of roots colonized by S. luteus to 39 and 77%, respectively, of the original rates. The Cu2+ 1-h shock treatment reduced the NH4+ uptake rate of NM plants by 51%.

Keywords: ectomycorrhiza; heavy metals; nutrient uptake rate; Paxillus involutus; Suillus luteus; Thelephora terrestris

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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