Preservation of Quercus Robur and Quercus Petraea Genetic Resources through In Vitro Culture

In this paper, the effect of various factors (clone, initial explant, sterilization method, and culture medium) on the in vitro multiplication of pedunculate and sessile oak species was tested. No influence of clone was found and a 44-83% survival rate was found for different types of explants, the best result being that of using mature acorns germinated in vitro. The most efficient sterilization method was: mercuric chloride 0.2 mg/l, ascorbic acid 1 mg/l, for 30 min., with or without antibiotic. The best results were obtained with GD medium complemented with 0.5 mg/l BAP and 0.1 mg/l IBA, which allowed obtaining of a high rooting percentage. The regenerated plants were transferred in vivo, in a climate controlled greenhouse.

Significance of current weather conditions for foliar traits of old-growth sessile oak (Quercus petraea Liebl) trees

Key message Sessile oak leaves showed a high degree of plasticity to atmospheric and pedospheric conditions. Abstract The aim of the present study was to elucidate the significance of current weather conditions for foliar traits of adult sessile oak (Quercus petraea), one of the most valuable forest tree species in Central Europe. For this purpose, structural and functional traits were analysed in fully expanded, sun exposed leaves collected in south-west Germany from five old-growth forest stands, representing the meteorological and pedospheric conditions in the growing region, but differing in aridity during the 12 days before harvest in two consecutive years. Across the forest stands, most foliar traits differed significantly between wet and dry weather conditions before harvest as indicated by partial least square discriminant analysis (PLS-DA). These traits included fresh weight/dry weight ratio, leaf hydration, leaf-C content, leaf-C/N ratio, structural N, soluble protein-N, total amino acid-N, cell wall composition, numerous specific amino acids as well as soluble sugar content. Structural biomass, δ13C signature, total N and total C as well as H2O2 contents were not affected by the weather before harvest. These results indicate a high plasticity of the foliar metabolism of drought-tolerant sessile oak to current weather conditions. They also suggest that sessile oak is characterized by a high potential to cope with the growth conditions expected as a consequence of future climate change.

Impact of Gene Flow and Introgression on the Range Wide Genetic Structure of Quercus robur (L.) in Europe

As for most other temperate broadleaved tree species, large-scale genetic inventories of pedunculate oak (Quercus robur L.) have focused on the plastidial genome, which showed the impact of post-glacial recolonization and manmade seed transfer. However, how have pollen mediated gene flow and introgression impacted the large-scale genetic structure? To answer these questions, we did a genetic inventory on 1970 pedunculate oak trees from 197 locations in 13 European countries. All samples were screened with a targeted sequencing approach on a set of 381 polymorphic loci (356 nuclear SNPs, 3 nuclear InDels, 17 chloroplast SNPs, and 5 mitochondrial SNPs). In a former analysis with additional 1763 putative Quercus petraea trees screened for the same gene markers we obtained estimates on the species admixture of all pedunculate oak trees. We identified 13 plastidial haplotypes, which showed a strong spatial pattern with a highly significant autocorrelation up to a range of 1250 km. Significant spatial genetic structure up to 1250 km was also observed at the nuclear loci. However, the differentiation at the nuclear gene markers was much lower compared to the organelle gene markers. The matrix of genetic distances among locations was partially correlated between nuclear and organelle genomes. Bayesian clustering analysis revealed the best fit to the data for a sub-division into two gene pools. One gene pool is dominating the west and the other is the most abundant in the east. The western gene pool was significantly influenced by introgression from Quercus petraea in the past. In Germany, we identified a contact zone of pedunculate oaks with different introgression intensity, likely resulting from different historical levels of introgression in glacial refugia or during postglacial recolonization. The main directions of postglacial recolonization were south to north and south to northwest in West and Central Europe, and for the eastern haplotypes also east to west in Central Europe. By contrast, the pollen mediated gene flow and introgression from Q. petraea modified the large-scale structure at the nuclear gene markers with significant west–east direction.

Foliar Fungal Endophytes in a Tree Diversity Experiment Are Driven by the Identity but Not the Diversity of Tree Species

Symbiotic foliar fungal endophytes can have beneficial effects on host trees and might alleviate climate-induced stressors. Whether and how the community of foliar endophytes is dependent on the tree neighborhood is still under debate with contradicting results from different tree diversity experiments. Here, we present our finding regarding the effect of the tree neighborhood from the temperate, densely planted and 12-years-old Kreinitz tree diversity experiment. We used linear models, redundancy analysis, Procrustes analysis and Holm-corrected multiple t-tests to quantify the effects of the plot-level tree neighborhood on the diversity and composition of foliar fungal endophytes in Fagus sylvatica, Quercus petraea and Picea abies. Against our expectations, we did not find an effect of tree diversity on endophyte diversity. Endophyte composition, however, was driven by the identity of the host species. Thirteen endophytes where overabundant in tree species mixtures, which might indicate frequent spillover or positive interactions between foliar endophytes. The independence of the diversity of endophytes from the diversity of tree species might be attributed to the small plot size and the high density of tree individuals. However, the mechanistic causes for these cryptic relationships still remain to be uncovered.

Oak Species Quercus robur L. and Quercus petraea Liebl. Identification Based on UHPLC-HRMS/MS Molecular Networks

Two species of oak are dominant in French forests: pedunculate oak (Quercus robur L.) and sessile oak (Quercus petraea Liebl.). Their differentiation is not straightforward but is essential to better understand their respective molecular content in order to better valorize them. Thus, to improve oak species identification, an untargeted UHPLC-HRMS/MS method associated with a two-step data treatment was developed to analyze a wide range of specialized metabolites enabling the comparison of both species of oak extracts. Pooled extracts from sessile and pedunculate oaks, composed of extracts from several trees of pure species from various origins, were compared using first the Venn diagram, as a quick way to get an initial idea of how close the extracts are, and then using a molecular network to visualize, on the one hand, the ions shared between the two species and, on the other hand, the compounds specific to one species. The molecular network showed that the two species shared common clusters mainly representative of tannins derivatives and that each species has specific molecules with similar fragmentation patterns, associated in specific clusters. This methodology was then applied to compare these two pooled extracts to unknown individuals in order to determine the species. The Venn diagram allowed for the quick presumption of the species of the individual and then the species could be assigned more precisely with the molecular network, at the level of specific clusters. This method, developed for the first time, has several interests. First, it makes it possible to discriminate the species and to correctly assign the species of unknown samples. Moreover, it gave an overview of the metabolite composition of each sample to better target oak tree utilization and valorization.

Історичний генезис та структура дендрофлори курортного парку у Брюховичах біля Львова

Наведено результати історичного аналізу та еволюції зелених насаджень курортного парку у смт Брюховичі, площею 10 га, закладеного на зламі ХІХ-ХХ ст. під керівництвом головного садівника Львова Арнольда Рерінга. Встановлено, що колишній курортний парк на сьогодні не є цілісним об'єктом та не має жодного природоохоронного статусу. З'ясовано, що територія парку зазнає значного антропогенного впливу, що позначилось на його фрагментації, деградації планувальної структури та поширенню забудови. Водночас спостерігається інтенсифікація його неконтрольованого заростання. У процесі історичного аналізу дендрофлори виявлено, що соснові насадження на території парку є зразком антропогенної сукцесії, яка розвивалася значно швидше, ніж лісова, а особливо в її третій стадії, коли в парку вже на початку ХХ ст. з'явилось багато листяних видів. За архівними та літературними джерелами проаналізовано планувально-стилістичні риси об'єкта та його дендрофлору. З'ясовано, що під час закладання парк формувався у пейзажному стилі, однак його видовий склад не оновлювався впродовж багатьох років, що призвело до втрати естетичності та декоративності. Виявлено, що сучасну дендрофлору парку формують 28 видів дерев і кущів, що належать до 13 родин. Встановлено, що вікова структура паркових насаджень є нерівномірною. Молоді і середньовікові особини охоплюють у середньому 20 % насаджень. Виявлено вікові особини Quercus petraea Liebl., Quercus robur L., Pinus sylvestris L. та Fagus sylvatica L., які потребують охорони. Вікові особини Quercus petraea, разом з молодими особинами формують унікальне для Львова оселище. З'ясовано, що на території парку місце декоративних видів зайняли лісові: Sambucus nigra L., Corylus avellana L., Euonymus verrucosa Scop. та E. europaea L., види роду Rubus L. Проаналізувавши дендрофлору за біоморфологічною структурою, виявлено, що панівною є група дерев – 20 видів. Із загальної кількості групи дерев переважають листопадні – 17 видів; вічнозелених є тільки 3 види. Група кущів – 8 видів, серед яких переважають листопадні (6 видів). Рівень збереженості цього парку оцінено на два бали. Об'єкт потребує подальшого моніторингу зелених насаджень та розроблення проєкту відновлення, впорядкування території та надання відповідного охоронного статусу.