Defence Is a Priority in Female Juveniles and Adults of Taxus baccata L.

Female individuals of dioecious plants invest their resources more in storage and defence, and the males have higher nitrogen content invested in the production of pollen grains. An unresolved problem is whether this strategy occurs only in sexually mature plants or can also occur in juvenile plants. To answer this, Taxus baccata (L.) needles from the mature plants and rooted cuttings (juveniles) in a pot experiment were compared for the content of carbon, nitrogen, starch, total non-structural carbohydrates (TNC), and total phenolic compounds (TPhC). The results indicate that the differences between sexes occurred mainly in sexually mature plants, where the starch content was higher in females and nitrogen in males. However, the novelty of the results is that TPhC was generally higher in females than males in both adults and juveniles, suggesting that defence is a priority for females from an early age. We do not know if this is an innate trait because the strobili production (albeit at a very low level) of juveniles was observed in all individuals after the autumn of the first year. We found no effect of fertilization on sex-specific response in the pot experiment, which may be related to the lower reproductive effort of juveniles

Effects of elevated temperature and fluorine pollution on relations between the pedunculate oak (Quercus robur) and oak powdery mildew (Microsphaera alphitoides)

Effects of elevated temperature and soil pollution with fluorine on host-pathogen relations were studied in seedlings of the pedunculate oak (Quercus robur L.) inoculated with oak powdery mildew (Microsphaera alphitoides Griff. et Maubl.) and control seedlings. The plants were grown for 1month in elevated temperature (on average by 1.6°C) and soil pollution with sodium fluoride (330 ppm F). The above factors did not have any significant effect on nitrogen content of leaves or on concentrations of metabolites favourable to growth and development of the fungal pathogen (total non-structural carbohydrates, including soluble carbohydrates and starch) and those unfavourable to fungi (soluble phenols, condensed tannins and lignins). The elevated temperature and fluorine pollution did not affect the leaf infection rate. However, a significant temperature × pollution interaction was observed in inoculated seedlings. At the elevated temperature, fluorine caused a less severe infection by powdery mildew. This could be due to a direct toxic effect of fluorine on the pathogen or by an indirect influence, resulting from changes in levels of other metabolites, which were not analysed in this study. The inoculation of oak seedlings with powdery mildew caused a decline in the carbohydrate content of leaves but did not have any significant effect on levels of other analysed metabolites. However, it significantly affected the distribution of phenols and lignins in oak leaves. Those compounds accumulated within necrotic lesions and in adjacent cells. Our results do not enable drawing definite conclusions on effects of a slight rise in temperature and a relatively low level of fluorine pollution of the soil on relations between the pedunculate oak and oak powdery mildew. Lower values of the leaf infection rate in seedlings growing in elevated temperature and fluorine pollution suggest that in warmer years a lower level of infection by M. alphitoides may be expected in areas affected by fluorine pollution

High genetic similarity between Polish and North European Scots pine (Pinus sylvestris L.) populations at nuclear gene loci

Nucleotide polymorphisms in a set of 32 nuclear genes were studied in 19 mountain, peatbog and lowland populations of Scots pine representing known phenotypic races and populations of presumably relict character for the species in Poland. At 29 genes, the pattern of genetic variation was compared to 11 reference populations from Northern, Western and Southern Europe. Similar levels of nucleotide polymorphism and excess of low-frequency mutations were observed in Polish populations (π tot = 0.0055, D = −0.308) and as compared to the reference samples (π tot = 0.0054, D = −0.170). Bayesian assignment and conventional frequency-based statistics indicate that Polish populations share the same genetic background at the analysed nuclear gene markers. However, the populations showed a much closer genetic relationship with North European samples than other regional groups of populations. Across the very uniform genetic background of the populations, we identified several genes with outlier patterns of haplotype, polymorphism frequency variation and departures from compound neutrality tests. Our data indicate that the Central and North European parts of the Scots pine distribution seem particularly suitable for association genetic studies to link phenotypic and genetic variation at a large geographical scale