A (1)H and (19)F nuclear magnetic resonance study of [Mg(H2O)6](BF4)2 has confirmed the existence of two phase transitions at Tc1 ≈ 257 K and Tc2 ≈ 142 K, detected earlier by the DSC method. These transitions were reflected by changes in the temperature dependences of both proton and fluorine of second moments M2 (H) and M2 (F) and of spin-lattice relaxation times T1 (H) and T1 (F). The study revealed anisotropic reorientations of whole [Mg(H2O)6](2+) cations, reorientations by 180° jumps of H2O ligands, and aniso- and isotropic reorientations of BF4 (-) anions. The activation parameters for these motions were obtained. It was found that the phase transition at Tc1 is associated with the reorientation of the cation as a whole unit around the C3 axis and that at Tc2 with isotropic reorientation of the BF4 (-) anions. The temperature dependence of the full width at half maximum value of the infrared band of ρt(H2O) mode (at ∼596 cm(-1)) indicated that in phases I and II, all H2O ligands in [Mg(H2O)6](2+) perform fast reorientational motions (180° jumps) with a mean value of activation energy equal to ca 10 kJ mole(-1), what is fully consistent with NMR results. The phase transition at Tc1 is associated with a sudden change of speed of fast (τR ≈ 10(-12) s) reorientational motions of H2O ligands. Below Tc2 (in phase III), the reorientations of certain part of the H2O ligands significantly slow down, while others continue their fast reorientation with an activation energy of ca 2 kJ mole(-1). This fast reorientation cannot be evidenced in NMR relaxation experiments. Splitting of certain IR bands connected with H2O ligands at the observed phase transitions suggests a reduction of the symmetry of the octahedral [Mg(H2O)6](2+) complex cation.

In this study, evolution of the genetic structure of the oldest known population of Dothistroma septosporum in Poland was analysed. Dothistroma needle blight was first recorded in Poland in 1990 in a 5‐year‐old plantation, meaning the population is relatively young in terms of evolution and genetic development. The preservation of DNA extracts from other studies allowed examination of the genetic variation of the pathogen over the span of a decade with the use of highly sensitive microsatellite markers. A number of evolutionary factors were identified that have shaped the genetic structure of this population over time. First, indications of the founder effect and the impact of selection were observed. Secondly, structure analysis provided evidence of the introduction of a new genetic component to the population structure after the pathogen had established. Finally, the impact of the reproductive mode on various components of the Domiarki population was examined, revealing the presence of genetic groups and structure clusters with varying levels of sexual recombination. These results demonstrate how well established and genetically robust a new population of a pathogen may become in just a few decades, given favourable conditions, and how new introductions may facilitate this process.

Fungal virulence may be studied using tissues cultures of host plants in dual cultures in vitro, enabling analyses of interactions with undifferentiated cells of their host plants. Three genotypes of Pinus sylvestris callus, initiated by somatic embryogenesis, were used for establishing dual cultures with fungi pathogenic, endophytic or saprotrophic on pine needles or shoots. Fungal growth towards the plant callus tissue differed, depending on the life strategy of the fungus. The pathogen Gremmeniella abietina proved the slowest colonizer of callus whereas the saprotrophic Phacidium lacerum was the fastest. Gremmeniella abietina partially overgrew the callus, causing extensive necrosis and death within 10 days after inoculation. Anthostomella formosa, an endophyte of pines, did not cause evident symptoms of callus degradation: after 10 days of dual culture, the callus cells remained greenish and at least 50% of cells were alive. In dual cultures Ph. lacerum, callus remained alive until the end of the experiment, maintaining a white-creamy colour with a loose cell structure. Electrophoresis of protein extracts from the callus showed the presence of additional bands of 25-35 kDa only in host tissues challenged with the pathogen G. abietina, possibly indicating the production of pathogenesis-related proteins. This work has shown that pine callus does not respond equally to challenge with different fungal isolates. In general, one-third of the isolates of each fungus examined showed greater virulence compared to other isolates.

Dothistroma septosporum is one of the most damaging fungi-attacking pines wherever they are grown. Specific symptoms on pine include the formation of red bands on needles and the appearance of which is attributed to dothistromin, a toxin produced by this pathogen. Many reports have suggested that such red bands do not appear in all infections, although the cause of this phenomenon is unclear. When grown in vitro, some strains of D. septosporum cause an intense blue, rather than red, coloration of the medium. This study presents results of experiments designed to determine the effects of culture conditions on growth of D. septosporum in vitro and the accompanying coloration of the medium. Growth of D. septosporum is characterized by slow mycelial extension and high morphological diversity in all culture conditions. The most rapid growth occurred at 20°C and on a medium at pH 6. Colour of the secreted pigment was not a consistent feature of a given fungal isolate, but depended on temperature and pH of the medium, along with a significant interaction among these factors. Lower temperature and lower pH favoured the production of the blue pigment. Moreover, pigmentation around the D. septosporum colonies was affected by other fungi inhabiting the same ecological niche. These results are discussed in terms of the possible reasons for the failure to produce the characteristic red banding symptoms on needles infected by D. septosporum in some in vivo situations.

This study describes a preliminary investigation of the occurrence of Tubakia dryina in Poland, based on fungal isolations from symptomless leaves and from necrotic areas of leaf blades of Quercus robur, Fagus sylvatica and Tilia cordata. Occurrence of T. dryina on leaves of the two latter species is reported for the first time. Frequency of incidence on different hosts varied between tree species, with the highest rate on oaks and the lowest on linden. The results also suggest the ubiquitous occurrence of T. dryina on oaks in Poland. This situation is in contrast to previous observations showing much lower frequency of this fungus in the past. A preliminary, ITS-based, analysis of genetic diversity among Polish isolates of T. dryina revealed the presence of two distinct haplotypes, both of which are widespread in Poland and occur on the same trees in most locations. No further genetic diversity was observed within either detected lineages using ITS analyses.