Umverteilung von Wasser im Boden durch das Myzel saprotropher Pilze und die Auswirkungen auf die C-Mineralisation in trockenen Böden
Zusammenfassung der Projektergebnisse
The desiccation of upper soil horizons is a common phenomenon leading to a decrease of soil microbial activity. Recent studies showed that fungal communities are often less sensitive and better adapted to soil desiccation than bacterial communities. Mechanisms behind this observation and general drought responses of filamentous saprotrophic fungi are only scarcely analysed. One reason for better fungal adaptation to desiccation may be hydraulic redistribution (HR) of water by mycelia networks. Yet, the relevance of HR by saprotrophic fungi with different foraging strategies and its impact on carbon (C) and nitrogen (N) turnover in soils is largely unknown. Here, we tested the potential of the litter decomposing species Agaricus bisporus and the wood decomposing fungus Schizophyllum commune for HR and compared it to capillary soil water transport. We further compared C mineralization and N translocation of the mycelium of S. commune and A. bisporus during simultaneous HR. In addition, we analysed transcriptional and respiratory responses of A. bisporus to drought stress and how they are impacted by the antioxidant riboflavin. A. bisporus and S. commune redistributed water at a flow velocity of about 0.3 cm min^-1 and 0.43 cm min^-1, respectively, in single hyphae. The amount of transferred water was similar to or even higher then capillary transport, suggesting that HR has the potential to overcome capillary barriers in soils. HR seems to partly compensate water deficiency if water is available in other zones of the mycelia network. It is likely a mechanism behind higher drought resistance of soil fungi compared to bacteria. While HR by A. bisporus strongly enhanced C mineralization and enzymatic activity in the previously dry soil, the impact of HR by S. commune on C mineralization was rather small. Further, S. commune redirected N towards the nutrient source while A. bisporus translocated N from the nutrient source towards other parts of the mycelia network. The impact of fungal HR on C mineralization and N translocation seems to be controlled by the fungal foraging strategy and the resource usage. The transcriptional response of A. bisporus to drought or riboflavin was mainly based on factors regulating transcription, translation and growth. This was even stronger in combined treatments. Further, riboflavin induced several protective mechanisms, methylglyoxal (cytotoxic byproduct of glycolysis) detoxifying lactoylglutathione lyase being most pronounced. Drought increased riboflavin content in hyphae about 5 times, with or without riboflavin addition. Without riboflavin addition, fungal respiration decreased by more than 50% at a water potential of about -20 MPa. Respiration remained about 2-3 times higher with riboflavin addition. These data indicate a priming function and a prominent role of riboflavin in drought responses of A. bisporus.
Projektbezogene Publikationen (Auswahl)
- 2015: Redistribution of soil water by a saprotrophic fungus enhances carbon mineralization. Proc Natl Acad Sci USA 112:14647–51
Guhr A, Borken W, Spohn M, Matzner E
(Siehe online unter https://doi.org/10.1073/pnas.1514435112) - Effect of water redistribution by two distinct saprotrophic fungi on carbon mineralisation and nitrogen translocation in dry soil. Soil Biol Biochem, Volume 103, December 2016, Pages 380-387
Guhr A, Marzini C, Borken W, Poll C, Matzner, E
(Siehe online unter https://doi.org/10.1016/j.soilbio.2016.09.009) - Vitamin B2 (riboflavin) increases drought tolerance of Agaricus bisporus. Mycologia, Volume 109, 2017 - Issue 6, 860-873
Guhr A, Horn MA, Weig AR
(Siehe online unter https://doi.org/10.1080/00275514.2017.1414544)
