N-Acetylglucosaminidase activity, a functional trait of chitin degradation, is regulated differentially within two orders of ectomycorrhizal fungi: Boletales and Agaricales
Chitin is one of the most abundant nitrogen-containing polymers in forest soil. Ability of ectomycorrhizal (EM) fungi to utilize chitin may play a key role in the EM symbiosis nutrition and soil carbon cycle. In forest, EM fungi exhibit high diversity, which could be based on function partitioning and trait complementarity. Although it has long been recognized that closely related species share functional characteristics, the phylogenetic conservatism of functional traits within microorganisms remains unclear. Because extracellular N-acetylglucosaminidase activity has been proposed as functional trait of chitin degradation, we screened this activity on 35 EM fungi species with or without chitin in the growth medium to (i) describe the functional diversity of EM fungi and (ii) identify potential links between this functional trait and EM fungal phylogeny. We observed large variations of the extracellular N-acetylglucosaminidase activities among the fungal strains. Furthermore, our results revealed two regulation patterns of extracellular N-acetylglucosaminidase activities. Indeed, these chitinolytic activities were stimulated or repressed in the presence of chitin, in comparison to the control treatment. These profiles of extracellular N-acetylglucosaminidase stimulation/repression might be conserved at a high phylogenetic level in the Basidiomycota phylum, as illustrated by the opposite patterns of regulation between Boletales and Agaricales. Finally, the downregulation of this activity by chitin, for some EM fungal groups, might suggest another chitin degradation pathway.
KeywordsChitin degradation Chitinase N-Acetylglucosaminidase Functional trait Fungal phylogeny
FM holds a PhD fellowship awarded by the Région Lorraine and the Laboratory of excellence ARBRE (BRIDGE project). We would like to thank Anais Gillet for the maintenance of the fungal strains collection.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest
- Baath E, Soderstrom B (1979) Fungal biomass and fungal immobilization of plant nutrients in Swedish coniferous forest soils. Rev Écol Biol Sol 16:477–489Google Scholar
- Dutta PK, Dutta J, Tripathi VS (2004) Chitin and chitosan: chemistry, properties and applications. J Sci Ind Res 63:20–31Google Scholar
- Pritsch K, Raidl S, Marksteiner E, Blaschke H, Agerer R, Schloter M, Hartmann A (2004) A rapid and highly sensitive method for measuring enzyme activities in single mycorrhizal tips using 4-methylumbelliferone-labelled fluorogenic substrates in a microplate system. J Microbiol Methods 58:233–241CrossRefPubMedGoogle Scholar
- R Core Team (2015) R: a language and environment for statistical computing. Vienna, Austria. http://www.R-project.org/