A total of 159 colonies of Chalara fraxinea were isolated between 2005 and 2006 from dying trees of European ash (Fraxinus excelsior L.) aged between 3 and 10 years. They derived from five regions of Poland differing by geographic location and climatic conditions. On the basis of 90 RAMS markers, pathogen intra-and inter-population variability, as well as its dependency on geographic distance and climatic conditions in the regions of strain origin, was analysed. The applied measures of intrapopulation genetic variability (genetic distance, Nei's unbiased diversity, Shannon's Information Index and percentage of polymorphic loci) allowed for differentiation of two strain groups: the first deriving from lowlands and the second from uplands and mountainous areas. Strains in lowlands were characterised by smaller number of markers, smaller number of polymorphic loci and smaller intrapopulation genetic variability. Positive and statistically significant correlation was shown between variability of isolates and elevation of regions above sea level. Pair-wise genetic distances between groups of isolates (Nei's unbiased genetic distance) from particular regions were not significantly correlated with the corresponding geographic distances. On the basis of AMOVA, it was shown that 85% of variability was within-region differences and 2% betweenregion differences, whereas differences between lowlands and uplands were 13%. Principal Components Analysis (PCA) for the investigated regions confirmed the results from Nei's genetic distance matrix.

Conditions for obtaining an efficient mass propagation procedure to overcome isolated Taxus baccata embryo dormancy were investigated. The protocol herein described was efficient for overcoming the dormancy of T. baccata isolated embryos under in vitro conditions, enabling the conservation and propagation of this species. T. baccata seeds were unable to germinate directly after collection under in vitro conditions. Very good sterility and germination was achieved by soaking seeds in distilled water at a low temperature (+4°C) at least for 48 h instead of leaching them for 7 d under running water, followed by maintaining isolated embryos on the Murashige and Skoog medium (MS) supplemented with 5 g l −1 activated charcoal. That treatment allowed one to shorten the time of the experiment and gave almost 100% sterility. The best germination was observed in darkness, but to obtain worthy seedlings, it was necessary to place cultures in a 16-h photoperiod after a 2-wk incubation. There was no significant difference in germination between seeds collected from different populations of Southern Poland.

High-altitude tree populations are exposed to severe natural environmental conditions. Among abiotic factors, variable temperatures, early frosts, and high radiation are the factors affecting tree growth at high altitudes. Fagus sylvatica L. exhibits a variety of physiological and genetic traits that allow it to adapt to different forest habitats. This study examines the differences in the biochemical properties of senescing beech leaves between populations originating from different altitudes using a common-garden experiment. Leaves were collected from five-year-old plants from the beginning of August to the end of October for two years. Based on the changes in senescence marker levels the genetic differences and significant correlations between populations’ altitude origin and their biochemical characteristics were identified. According to the free radical theory of leaf senescence, reactive oxygen species (ROS) and senescence markers were highly correlated. In this study, populations from higher altitudes were characterized by earlier and greater increases in ROS content and oxidative stress, which resulted in higher antioxidative system activity. Increases in ROS in high-altitude populations play a controlling role to initiate earlier senescence processes that allow the trees to adapt to harsh climatic conditions. Earlier senescence allows beech trees to maintain a balance between nitrogen metabolism and photosynthetic activity. It allows for remobilization of nitrogen compounds more efficiently and protects the trees from nitrogen loss and prepares them for winter dormancy.

Yew is a coniferous, evergreen, dioecious species. The objective of the study was to present a comprehensive characteristic of changes occurring throughout the year in terms of the content of photosynthetic pigments and related compounds in the needles of yew, depending on the sex of individuals and age of needles. Eight compounds, particularly chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoids (Car), protoporphyrin IX (PPIX), magnesium protoporphyrin IX (MgPPIX), protochlorophyllide (Pchlide), chlorophyllide a (Chlide a), and chlorophyllide b (Chlide b), were subjected to quantitative analysis. Based on the several parameters under study, significant differences between male and female individuals were observed, while most commonly, the largest differences were reported in the autumn and winter period. They were related to the content of Chl a, Chl b and Chl/Car ratio. The remaining compounds showed no significant differences according to the sex and were slightly different only in single periods. For all the studied parameters except for Chl/Car ratio, interaction between sampling dates and sex was not statistically significant. Significant differences between the needles of different age were observed only in terms of the content of Chl b, MgPPIX, Pchlide, Chlide b, and Chl a/b ratio, and these differences were always caused by the current-year needles.

A b s t r a c tEighty-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.