 |
| Titel |
Nutrient availability controls the decomposition activities of the ectomycorrhizal fungi Paxillus involutus and Laccaria bicolor |
| VerfasserIn |
César Nicolás, Tomas Martin-Bertelsen, Johan Bentzer, Tomas Johansson, Mark Smits, Carl Troein, Per Persson, Anders Tunlid |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151206
|
| Publikation (Nr.) |
 EGU/EGU2017-15767.pdf |
|
|
|
|
|
| Zusammenfassung |
| Ectomycorrhizal (ECM) fungi play an important role in the ecological sustainability of
northern temperate and boreal forests by foraging and mining soil organic matter for
nutrients to their host plants. In this process, the fungal partner provides the plant
host with nutrients and receives in return carbon, which supports the growth of
extramatrical mycelium. Here, we examine the chemical changes in the soil organic
matter (SOM) and physiological response of two species of ECM fungi Paxillus
involutus and Laccaria bicolor during the decomposition of SOM and utilization of
glucose.
These two ECM fungi were grown in axenic cultures containing a water extract of organic
matter (WEOM), which was supplemented with glucose at the start of the experiment. The
fungi then went through two phases: a decomposition phase characterized by a WEOM with
glucose followed by a starvation phase, with no glucose left in the media. The chemical
modifications in the WEOM were followed using techniques such as infrared and X-ray
absorption spectroscopy, while the fungal physiological response was studied using
transcriptomic (RNAseq) analysis.
The spectroscopic techniques showed that both fungi enhanced the amount of
oxidized compounds while uptaking glucose or nitrogen from the media. In case of P.
involutus, this oxidation process was more pronounced than that occurring with L.
bicolor. In addition, the X-ray absorption spectroscopy showed a higher reduced iron
content in WEOM incubated with P. involutus in comparison to L. bicolor, which
may suggest the preference of P. involutus for oxidative mechanisms via Fenton
chemistry.
During the decomposition phase, both fungi expressed a large number of transcripts
encoding proteins associated with oxidation of lignocellulose in wood decomposing fungi. In
parallel, the expression levels of extracellular peptidases, and enzymes involved in the
metabolism of amino acids and assimilated glucose were regulated. However, during
prolonged starvation, transcripts encoding extracellular enzymes such as peptidases and
laccases were upregulated concomitantly with transporters and metabolic enzymes,
which suggest that some of the released cellular material were re-assimilated by the
mycelium.
These results show the concomitant changes in gene expression of EMF and in nutrient
availability in the WEOM and reveal the combination of transcriptomic and spectroscopic
techniques as a useful tool to better understand the decomposition process in soil. |
|
|
|
|
|
|