Relative abundance of ectomycorrhizas in a managed loblolly pine (Pinus taeda) genetics plantation as determined through terminal restriction fragment length polymorphism profiles

We examined the relationship between relative abundance of ectomycorrhizas in soil cores determined using morphotype tip counts and terminal restriction fragment length polymorphism (TRFLP) analysis. Root tips were harvested from a total of 120 soil cores collected from six family plots in a loblolly pine (Pinus taeda L.) genetics plantation. Tips from each soil core were morphotyped based on physical characteristics, identified through TRFLP and sequence analysis, then pooled to reconstruct the ectomycorrhizal community within that core. The identity and relative abundance of specific ectomycorrhizas in each reconstructed community was then determined using TRFLP analysis of the internal transcribed spacer of the rRNA gene. Using TRFLP, we were able to detect 34 ectomycorrhizal phylotypes colonizing roots of loblolly pine. TRFLP peak area was an accurate approximation of the relative number of tips of each ectomycorrhizal type within a soil core. Relative abundance of each ectomycorrhiza as determined by TRFLP was used to describe their distribution in the pine plantation. Although there were no differences found in ectomycorrhizal richness and evenness among the six family plots, the two fertilized plots had generally lower levels of ectomycorrhizal richness and evenness as indicated by rank abundance curves. Our results suggest that TRFLP is a useful tool for describing the occurrence and distribution of ectomycorrhizas in environmental samples.