Genome ecology of ectomycorrhizal fungi
The aim of the project is to identify the extracellular enzymes and other proteins that are secreted by the ectomycorrhizial (EM ) fungus Paxillus involutus during the degradation and transformation of organic material, and examine how these activities affect the stability of soil carbon (C), and how they are regulated in response to changes in the environment. Comparative studies will be done with other EM fungi showing different types of exploration. Based on these data, we will develop molecular markers that can be used to follow C transformation and sequestration by EM fungi in forest ecosystems.
Ectomycorrhizal (EM) fungi form mutualistic relationships with the roots of woody plants. During the symbiosis the two organisms exchange C and nutrients. The plant-derived C supports the growth of a large fungal mycelium that colonizes the soil. This translocation provides a dominant pathway by which C enters the pool of organic matter in forest soils. l. When encountering a patch of organic nutrients, the mycelium proliferates extensively and the finely branched hyphae secrete a wide range of enzymes that degrade the organic material. The released nutrients, in particular nitrogen (N) are taken up by the fungus and transferred to the plant. Though poorly characterized, the capture of nutrients from litter material by EM fungi is a key process regulating both nutrient cycling and plant C allocation in forest soils.