Garlic mustard (Alliaria petiolata), a plant of European-Asian origin, has encroached upon the woodland habitat of native Wisconsin species.  One strategy (of many) that A. petiolata employs to out-compete native species, is the secretion of allelopathic chemicals that inhibit the growth of specific mycorrhizal fungi required for tree seedling growth. To better understand the impact of A. petiolata on soil microbial diversity, we analyzed A. petiolata-invaded (GM) and non-invaded (NGM) soils from a Wisconsin old-growth wood for a difference in fungal species richness.  Soil samples were collected from paired experimental plots in Renak-Polack Woods, a beech-maple woods.  DNA isolated from the soil samples was subsequently used as the template in PCR with fungal-specific primers to amplify the ITS region of the ribosomal RNA gene.  The PCR products were subsequently ligated to a plasmid vector. The ligation mixture was used to transform Escherichia coli cells which were then plated on selective medium.  Recombinant plasmids were purified from the resulting plasmid libraries of GM- and NGM- derived fungal sequences. DNA sequencing and bioinformatics were used to identify the sources of the cloned sequences.

Results/Conclusions

Preliminary results indicate that soil fungal diversity was markedly lower than bacterial species diversity in the same area. Comparisons of NGM and GM samples revealed that the GM-invaded soils are vastly reduced in the species richness, with one member of the Basidiomycota as the predominant species.  This result is evidence that the presence of A. petiolata does alter the fungal community composition.