The influence of different stresses on glomalin levels in an arbuscular mycorrhizal fungus--salinity increases glomalin content

• Published in: PloS one 2011-12, Vol.6 (12), p.e28426-e28426
• Main Authors: Hammer, Edith C, Rillig, Matthias C
• Format: Article
• Language: English
• Subjects: Agriculture; Aquaporins; Arbuscular mycorrhizas; Arid zones; Benefit cost analysis; Binding sites; Biologi; Biological Sciences; Biology; Biomass; Carbon; Collembola; Computer Simulation; Cost benefit analysis; Ecosystem biology; Ecosystems; Environmental stress; Flowers & plants; Folsomia candida; Fungal Proteins - metabolism; Fungi; Gene expression; Glycerol; Glycine max; Glycoproteins; Glycoproteins - metabolism; Grazing; Hyphae; Lactuca sativa; Metabolism; Mycelium - drug effects; Mycorrhizae - drug effects; Mycorrhizae - growth & development; Mycorrhizae - metabolism; Mycorrhizae - physiology; Natural Sciences; Naturvetenskap; Osmolar Concentration; Osmosis - drug effects; Osmotic stress; Physiological aspects; Proteins; Salinity; Salinity effects; Sodium chloride; Sodium Chloride - pharmacology; Soil microorganisms; Soil sciences; Soil structure; Stress, Physiological - drug effects; Stresses; Sucrose
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0028426

Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and the soil fraction containing glomalin is correlated with soil aggregation. Thus, factors potentially influencing glomalin production could be of relevance for this ecosystem process and for understanding AM fungal physiology. Previous work indicated that glomalin production in AM fungi may be a stress response, or related to suboptimal mycelium growth. We show here that environmental stress can enhance glomalin production in the mycelium of the AM fungus Glomus intraradices. We applied NaCl and glycerol in different intensities to the medium in which the fungus was grown in vitro, causing salinity stress and osmotic stress, respectively. As a third stress type, we simulated grazing on the extraradical hyphae of the fungus by mechanically injuring the mycelium by clipping. NaCl caused a strong increase, while the clipping treatment led to a marginally significant increase in glomalin production. Even though salinity stress includes osmotic stress, we found substantially different responses in glomalin production due to the NaCl and the glycerol treatment, as glycerol addition did not cause any response. Thus, our results indicate that glomalin is involved in inducible stress responses in AM fungi for salinity, and possibly grazing stress.