Molecular characterisation of Discula quercina: a fungus involved in oak decline.

Endophytic fungi might be involved in the induction of oak decline, a disease with complex aetiology reported in Italy since 1980’s. Discula quercina, a well known endophytic fungus, was frequently isolated from Quercus cerris and Q. pubescens stands in north and central Italy, during 2001-2003. To improve the knowledge on the phylogeny and pathological attitude of this micro-organism, which is also known as the causal agent of oak anthracnose, an intraspecific study of all the isolates was carried out. ITS1-5.8S-ITS2 of rDNA, b-tubulin, actin, elongation factor, mitochondrial small subunit and GPD (glyceraldehyde phosphate dehydrogenase) regions of genomic DNA of D. quercina isolates were amplified and the sequences were aligned. Although the phylogenetic analyses are still at the beginning, nucleotide divergence was estimated in sequences of ITS1-5.8S-ITS2 ribosomal DNA, b-tubulin and actin genes. According to preliminary results, all isolates tested can be divided in two “groups”, that seems to be correlated with the host oak species. Morphometrical, enzymatic and pathogenetic analyses are in progress to support and confirm the existence of races within D. quercina species.