High resolution characterization of ectomycorrhizal fungal-mineral interactions in axenic microcosm experiments
- 465 Downloads
Microcosms with Pinus sylvestris seedlings in symbiosis with the fungus mycorrhizal Paxillus involutus were established, and atomic force microscopy (AFM) was used to characterise plant photosynthate-driven fungal interactions with mineral surfaces. Comparison of images of the same area of the minerals before and after mycorrhizal fungal colonization showed extensive growth of hyphae on three different mineral surfaces – hornblende, biotite and chlorite. A layer of biological exudate, or biolayer, covered the entire mineral surface and was composed of globular features of diameter 10–80 nm, and the morphology of the biolayer differed among mineral types. Similar-sized components were found on the fungal hyphae, but with a more elongated profile. Biolayer and hyphae surfaces both appeared to be hydrophobic with the hyphal surfaces yielding higher maximal adhesive interactions and a wider range of values: the mean (± SE) adhesive forces were 2.63 ± 0.03 and 3.46 ± 0.18 nN for biolayer and hypha, respectively. The highest adhesion forces are preferentially localized at the hyphal surface above the Spitzenkörper region and close to the tip, with a mean interaction force in this locality of 5.24 ± 0.49 nN. Biolayer thickness was between 10 and 40 nm. The underlying mineral was easily broken up by the tip, in contrast to the native mineral. These observations of mineral surfaces colonised by mycorrhizal fungus demonstrate how fungal hyphae are able to form a layer of organic exudates, or biolayer, and its role in hyphal attachment and potential weathering of ferromagnesian silicates, which may supply nutrients to the plant.
KeywordsEctomycorrhizal fungi Hyphae Mineral weathering Biolayer AFM Force mapping
This work was funded by the Natural Environment Research Council (NERC), consortium grant no NE/C521044/1, and is part of the Weathering Science Consortium (WSC) project on mineral weathering. This research project closely collaborates with MISSION ‘Mineral Surface Science for Nanotechnology’, a Marie Curie Early Stage Training Scheme (MEST-CT-2005-020828).
- Deer WA, Howie RA, Zussmann J (1992) The rock-forming minerals, 2nd edn. Longman Group (FE) Limited, Hong Kong, p 696Google Scholar
- Dufrêne YF, Boonaert CJP, Gerin PA, Asther M, Rouxhet PG (1999) Direct probing of the surface ultrastructure and molecular interactions of dormant and germinating spores of Phanerochaete chrysosporium. J Bacteriol 181:5350–5354Google Scholar
- Le Quéré A, Wright DP, Söderström B, Tunlid A, Johansson T (2005) Global patterns of gene regulation associated with the development of ectomycorrhiza between birch (Betula pendula Roth.) and P. involutus (Batsch) Fr APS 18:659–673Google Scholar
- Leake JR, Read DJ (1997) Mycorrhizal fungi in terrestrial habitats. In: Wicklow DT, Söderström B (eds) The mycota. Environmental and microbial relationships. Springer Verlag, Berlin, pp 281–301Google Scholar
- Leake JR, Duran AL, Johnson I, Bonneville S, Smits MM (2009) Hydroxyapatite weathering by pine mycorrhizas – the role of oxalic acid. Geochim Cosmochim Acta 73:A732Google Scholar
- Saccone L, Gazze SA, Ragnarsdottir KV, Leake JR, Duran AL, Hallam KR, McMaster TJ (2009) P. involutus hyphae: imaging their structure and interaction with mineral surfaces using AFM. Geochim Cosmochim Acta 73:A1140Google Scholar
- Schmalenberger A, Duran AL, Leake JR, Romero-Gonzales ME, Banwart SA (2009) Mineralogy controls oxalic acid release in mycorrhizal weathering. Geochim Cosmochim Acta 73:A1177Google Scholar
- Sirghi L, Kylián O, Gilliland D, Ceccone G, Rossi F (2006) Cleaning and hydrophilization of atomic force microscopy silicon probes. J Phys Chem 110:25975–25981Google Scholar
- Smith SE, Read DJ (2008) Mycorrhizal symbiosis, 2nd edn. Academic Press, San DiegoGoogle Scholar
- Tortonese M, Kirk M (1997) Characterization of application specific probes for SPMs. P Soc Photo-Opt Ins Proc 3009:53–60Google Scholar
- Wösten HAB, de Vries OMH, Wessels JGH (1993) Interfacial self-assembly of a fungal hydrophobin into a hydrophobic rodlet layer. Plant Cell 5:1567–1574Google Scholar