Differentiation and genetic structure of Sclerophoma pythiophila (Corda) v. hoehn. strains associated with various damage and disease symptoms on Pinus sylvestris L.

Eighty-three strains of Sclerophoma pythiophila were isolated in the period between 1996 and 2006 from needles and shoots of Pinus sylvestris displaying various types of disease symptoms or damages caused by Contarinia baeri or Thecodiplosis brachyntera. On the basis of fifty-six RAMS markers, very high genetic variability of examined strains was ascertained (mean value of Jaccard's coefficient 0.58). The highest genetic similarity was shown by strains related with needles damaged by Contarinia baeri (0.65), whereas the lowest by those derived from dead shoot tips (0.53). No monomorphic markers were found for individual groups of strains, yet on the basis of Nei's genetic distance matrix, it was possible to determine a group of closely related fungus populations which was connected with the damaging of the needles by C. baeri or T. brachyntera (Nei's coefficient ranging from 0.035 to 0.059) and populations related with the occurrence of necrosis on shoots or decay of their tips (Nei's coefficient - 0.066). The PCA confirmed genetic similarity of strains related with damaging of the needles by insects and strains isolated from local necroses on shoots and withered shoot tips. A high level of genetic variability between populations was shown by AMOVA analysis. A high level (14.9%) and statistically significant (P=0.001) share of between-population genetic variability were ascertained