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- Ekblad, Alf, 1957-, et al.
(författare)
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Determination of chitin in fungi and mycorrhizal roots by an improved HPLC analysis of glucosamine
- 1996
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Ingår i: Plant and Soil. - 0032-079X .- 1573-5036. ; 178:1, s. 29-35
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Tidskriftsartikel (refereegranskat)abstract
- A method to measure chitin content in fungi and ectomycorrhizal roots with high-performance liquid chromatography (HPLC) was developed. Measurements of fluorescence of 9-fluorenylmethylchloroformate (FMOC-CI) derivatives of glucosamine were made on acid hydrolysates of pure chitin, chitin-root mixtures and fungal-root mixtures. The method was applied on 5 isolates of ectomycorrhizal fungi, and ectomycorrhizal and non-mycorrhizal Pinus sylvestris roots. Interference from amino acids was removed by pre-treatment of samples with 0.2 N NaOH. This pre-treatment did not reduce the recovery of chitin, nor did plant material affect the recovery of chitin. The HPLC method was compared with a colorimetric chitin-method by measurements on root-fungal mixtures, with known fungal content. The HPLC method gave estimates of fungal biomass which were equal to the expected while the colorimetric method showed values significantly (p<0.001) lower than the expected. The present chitin method offers a sensitive and specific tool for the quantification of chitin in fungi and in ectomycorrhizal roots.
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| 4. |
- Olsson, P.A., et al.
(författare)
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Growth of arbuscular mycorrhizal mycelium in calcareous dune sand and its interaction with other soil microorganisms as estimated by measurement of specific fatty acids
- 1998
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Ingår i: Plant and Soil. - 0032-079X. ; 201:1, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- Fatty acid analysis was used for determining the extent of the development of the external mycelium of AM fungi (mixed inoculum from a sand dune) growing from roots of Festuca rubra and Plantago lanceolata in calcareous dune sand. The plants were raised in chambers specially designed to permit the growth of AM mycelium in root-free compartments. In two separate experiments, growth of external mycelium in the root-free compartments was detected and the amount of mycelium was estimated using the indicator of AM fungal biomass, phospholipid fatty acid (PLFA) 16:1 omega 5. The results showed that the PLFA 16:1 omega 5 was suitable for estimating the mycelium emerging from the mixed inoculum obtained from the field roots of F: rubra and P lanceolata. The PLFA 16:1 omega 5 showed external mycelium to become established in the root-free compartments within a period of 3 weeks and the amount of mycelium to continue to increase at 6 and 9 weeks. Increases in neutral lipid fatty acid (NLFA) 16:1 omega 5 (indicator of storage lipids) over time were inconsistent between the two experiments, but appeared to follow patterns of sporulation in each experiment. In both experiments, the root-free compartment was colonised by saprophytic fungi to a greater extent in the case of non-mycorrhizal than of AM treatment, as indicated by an increase in PLFA 18:2 omega 6,9 (indicator of saprophytic fungi). The absence of an increase in the case of AM treatment indicates that AM fungal mycelium can negatively affect the growth of saprophytic fungi in this soil type. This result was, however, only weakly supported by measurements of ergosterol content. The analysis of bacteria specific PLFAs showed that bacterial biomass was not affected by the AM mycelium.
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| 5. |
- Wallander, Håkan, et al.
(författare)
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Uptake of N-15-labelled alanine, ammonium and nitrate in Pinus sylvestris L. Ectomycorrhiza growing in forest soil treated with nitrogen, sulphur or lime
- 1997
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Ingår i: Plant and Soil. - 0032-079X. ; 195:2, s. 329-338
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Tidskriftsartikel (refereegranskat)abstract
- The uptake of N-15-labelled alanine, ammonium and nitrate was studied in ectomycorrhizal morphotypes of intact Pinus sylvestris seedlings. PCR-RFLP analysis of the ITS-region of fungal rDNA was used to identify the morphotypes. Seedlings were grown in forest soil collected at an experimental site in southern Sweden. The treatments compared were a control, N fertilisation (600 kg N ha(-1) as urea), sulfur application (1200 kg S ha(-1)) and lime application (6000 kg CaCO3 ha(-1)). The forest, which had been dominated by Picea abies, was clear-cut two years before the forest soil was sampled. Soil was also collected from an adjacent standing forest. The aim of the present study was to detect changes in the ectomycorrhizal communities in forest soils and relate these changes to the functional parameter of uptake of nitrogen from organic (alanine and protein) and inorganic (ammonium and nitrate) sources. Liming resulted in the detection of a morphotype not found in other samples, and one morphotype was only found in samples from the standing forest (the fungi in these two morphotypes could not be identified). All mycorrhizal root tips showed a higher N-15 concentration after exposure to different nitrogen forms than non-mycorrhizal long roots. Uptake of N-15 from a labelled solution of alanine or ammonium was higher (about tenfold) than uptake from a N-15-labelled solution of nitrate. Uptake of ammonium and alanine varied between 0.2 and 0.5 mg N g(-1) h(-1) and between 0.1 and 0.33 mg N g(-1) h(-1), respectively, among the different morphotypes. In seedlings grown in the control soil and in soil from standing forest, alanine and ammonium were taken up to a similar degree from a supply solution by all morphotypes, whereas ammonium uptake was higher than alanine uptake in seedlings grown in lime-treated soil (about twofold) and. to a lesser extent, in the nitrogen-and sulfur-treated soils. The higher ammonium uptake by morphotypes from the limed soil was confirmed in pure culture studies. In cases where ammonium was used as the N source, an isolate of the S. variegatus morphotype collected in the limed soil produced more biomass compared with isolates of S. variegatus collected in nitrogen or sulphur-treated soil. One isolate of a silvery white morphotype produced about equal amounts of biomass on alanine and ammonium, whereas all S. variegatus isolated performed better with ammonium as their N source. Based on the results it is hypothesised that liming can induce a shift in the ectomycorrhizal community, favouring individuals that mainly utilise inorganic nitrogen over those that primarily utilise organic nitrogen
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