Carbon availability triggers the decomposition of plant litter and assimilation of nitrogen by an ectomycorrhizal fungus

ABSTRACT: Abstract: A large part of the nitrogen in forest soils is found in recalcitrant organic matter-protein complexes. Ectomycorrhizal fungi are thought to have a key role in the decomposition and mobilization of nitrogen from such complexes. The knowledge on the functional mechanisms of these processes, and how they are regulated by carbon from the host plant and the availability of more easily available forms of nitrogen sources are limited. We used spectroscopic analyses and transcriptome profiling to examine how the presence/absence of glucose and ammonium regulates the decomposition and mobilization of nitrogen from litter material by the ectomycorrhizal fungus Paxillus involutus. Amendments of glucose triggered the assimilation of nitrogen and the decomposition of the litter material. Concomitantly, the expression of genes encoding enzymes involved in oxidative (i.e. Fenton chemistry) degradation of polysaccharides and polyphenols, peptidases, nitrogen transporters and enzymes in pathways of the nitrogen and carbon metabolism were upregulated in concert. Addition of ammonium had minute effects on both the expression of transcripts and decomposition of litter material, and only when glucose was present. Based on the spectroscopic analyses, three major types of chemical modifications of the litter material were observed. Each of them was correlated with the expression of specific sets of genes encoding extracellular enzymes. Our data suggests that the expression of the decomposition and nitrogen assimilation machinery of ectomycorrhizal fungi can be firmly regulated by the host carbon supply, i.e. priming, and that the availability of inorganic nitrogen as such has limited effects on the saprotrophic activities. Rineau F, Shah F., Smits M.M., Persson P., Johansson T., Carleer R., Troein C., Tunlid A. (2013) Carbon availability triggers the decomposition of plant litter and assimilation of nitrogen by an ectomycorrhizal fungus (submitted)

ORGANISM(S): Paxillus involutus ATCC 200175

PROVIDER: GSE45303 | GEO | 2013/04/30

SECONDARY ACCESSION(S): PRJNA193482

REPOSITORIES: GEO