Investigation of the influence of prescribed burning on ITS profiles of ectomycorrhizal and other soil fungi at three Australian sclerophyll forest sites

Abstract

DNA was extracted from soil collected from the upper 15 cm of the profile at three sclerophyll forest sites in New South Wales three days before, and 14 d after prescribed burning events. rDNA internal transcribed spacer (ITS) regions were amplified by PCR using fungus-specific primers, and ITS products cloned. Restriction fragment length polymorphism (RFLP) analysis was conducted on the ITS clones using the endonucleases HaeIII, HinfI, MboI and AluI. Cloned ITS products from the three sites were thus separated into 120 RFLP types and the ITS product for each RFLP type was sequenced. Comparison of sequences with those available in the GenBank nucleotide database allowed putative assignment of ITS clones to the following functional groups: ectomycorrhizal (ECM), arbuscular mycorrhizal (AM), ericoid mycorrhizal (ERM), decomposer basidiomycetes (DEC), other soil fungi (OSF). While abundant ECM-like clones were amplified from pre-fire soils at the North Rocks and South Maroota sites, they were largely absent in the post-fire soils at these sites, being replaced mainly by microfungi. In contrast, no decrease in ECM-like ITS clones was observed at the Ridgecrop site following fire. The data indicate that, while the abundance of extraradical ECM fungal propagules in the upper soil profile may be reduced by prescribed burning, the effect is site-specific.