Using mRNA differential display we have identified differentially expressed genes in non-self-interacting vs. single mycelia of the conifer pathogen Heterobasidion annosum and the wood decomposing basidiomycete Physisporinus sanguinolentus. Altogether 39 differentially displayed bands were cloned and sequenced, corresponding to 21 unique genes, which were confirmed by semi-quantitative RT-PCR to be differentially expressed. Further confirmation of differential gene expression was made by real time RT-PCR. All 10 genes identified from P. sanguinolentus had lower expression, while in H. annosum three genes had higher and eight lower expression in non-self-interacting mycelia vs. single mycelia. One of the induced genes showed high similarity to the Coprinus cinereus recA/RAD51 homolog (rah1) which is essential for homologous recombination, DNA repair and stress responses.

The feasibility of using coumarin-3-carboxylic acid (3-CCA) for detection of hydroxyl radicals in pure cultures of wood-decaying fungi was tested. Fungi were incubated on a 3-CCA-containing medium. The transformation of 3-CCA to the fluorescent hydroxyl radical detector substance 7-hydroxycoumarin-3-carboxylic acid and other compounds was studied by chromatographic and spectroscopic techniques. During incubation of all tested fungi, a small fraction of the 3-CCA was hydroxylated to 7-hydroxycoumarin-3-carboxylic acid and a major fraction of the 3-CCA was metabolized by fungi to 2-(2-hydroxybenzyl)malonic acid. In most cultures the concentration of 3-CCA was below detection limit at the end of incubation. The fungal metabolism was suggested to be involved in the formation of 2-(2-hydroxybenzyl)malonic acid from 3-CCA, consequently making this method of hydroxyl radical detection less suitable to use on cultures of wood-decaying fungi.