Enzyme production in the rhizosphere of paper birch and Douglas-fir along a chronosequence
Extramatrical mycelia are the most poorly understood and difficult to study component of the mycorrhizal symbiosis. Most studies have focused on mycorrhizal root tips because they are easier to see and separate from the soil for analysis. However, it is the extramatrical hyphae that act as the main nutrient absorbing interface between mycorrhizas and the soil. The extramatrical hyphae can mobilize soil nutrients by secreting hydrolytic enzymes or organic acids. Some of this activity in the mycorrhizosphere may be as a result of the activity of associated bacteria.
We will use a chronosequence of sites in the Interior Cedar Hemlock zone to determine whether ectomycorrhizal fungal communities and their associated bacteria differ functionally over successional time. Our earlier work established that the species composition of ECM fungal communities differed between clearcuts and forests, but we have yet to determine how these taxonomic differences relate to functional differences. We will start by quantifying phosphatase activity in situ using a colorimetric test applied to soil faces accessed through. Plexiglas root windows. We will then sample soil from areas of soil with high and low enzyme activities. A detailed molecular analysis of the bacterial and fungal communities will allow us to determine which micro-organisms are associated with this activity and whether this changes over succession in these forests. This will be one of the first studies to determine functional specificity of microbial communities in the field.
This work will be conducted by Denise Brooks. A major collaborator is Sue Grayston.
Last reviewed 4/8/2015 12:32:08 PM