Search

Pollen storage belongs among the most important activities associated with pollen handling. It overcomes the differences in pollen shedding and ovule receptivity during controlled pollination experiments. It is especially important for species like common juniper (Juniperus communis L.) with an extremely low quality of seeds due to pollination failure. Additionally, it is a substantial part of germplasm preservation programmes in pollen banks. In the present paper, the effect of short-term storage of pollen was studied using pollen samples from five shrubs in an in vitro germination test. Two temperature regimes were tested. The pollen viability of freshly collected pollen varied considerably between individual shrubs, exhibiting 67.3–88.6% germination rate and 248.0–367.3 µm of pollen tubes. Storage at + 4 °C for four months was accompanied by a profound decline in pollen viability. The germination percentage was reduced to 49.2–75.2% and the pollen tube length to 32.5–69.0%, depending on individual shrubs. The corresponding decline in pollen viability characteristics during storage at − 20 °C was only negligible in two of the tested shrubs. In the remaining three shrub samples, an increase in germination percentage was observed. Pollen tube growth responded more sensitively to freezing, but, on average, the decrease in length was lower than that at + 4 °C. The rate of reduction in pollen tube length varied between 11.5 and 45.4%. Cytological events accompanying in vitro germination of freezer-stored pollen exhibited some delay in releasing the exine from pollen grains during the early stages of germination as compared with freshly collected pollen. In conclusion, short-term storage of the common juniper pollen in a freezer is better for the preservation of its viability than storage at + 4 °C. [ABSTRACT FROM AUTHOR]

The editors would like to express their sincere gratitude to the following reviewers for their precious time and dedication, regardless of whether the papers were finally published: Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that I Applied Sciences i maintains its standards for the high quality of its published papers. [Extracted from the article]

Specific activity dynamics and isozyme composition of antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) were followed during the vegetation period in the young needles of Pinus mugo Turra, P. sylvestris L. and their putative hybrids. Tested enzymes differed in their dynamics showing the highest APX and CAT activities in the spring and autumn and the highest SOD activity in summer. The outlined course of enzyme activity was characteristic for all the three taxa compared. The level of specific enzyme activities was relatively constant in investigated taxa reaching statistical significance in some months of the scored period only. The same was true of the antioxidant enzyme activities of P. mugo individuals growing at different altitudes. Of the enzymes assayed, catalase was the most active. Hybrid individuals exhibited prevailingly intermediate level of their enzyme activity compared to the parental species. The dynamics of SOD correlated with intensity of UV irradiation during vegetation period. Partial correlation was observed between specific enzyme activities and isozyme composition. [ABSTRACT FROM AUTHOR]

The assisted migration of resistant seeds and seedlings may be a key to mitigating the effects of climate change on the productivity and composition of forest ecosystems. These efforts require an understanding of the intraspecific variability in the response of trees to extreme weather events such as heat waves. In this study, we assessed the geographical patterns of photosystem II (PSII) performance and thermostability in European beech (Fagus sylvatica L.) and whether intraspecific differences are associated with climate of origin. Two provenance trials with starkly contrasting climates were used for this study. Leaves were sampled both before and after natural heat stress exposure. Rapid chlorophyll fluorescence kinetics was used to evaluate PSII performance and PSII thermostability after simulated heat stress. The performance of PSII at 30 °C, which is still considered a non-damaging temperature, was generally slightly better at the warmer location than at the colder location. The populations originating closer to the Slovenian refugium, as well as those growing closer to their site of origin, showed better performance of PSII but not greater thermostability. The effect of simulated heat stress was much stronger in the colder plots compared to the warmer plots, but only for previously stressed trees. Likewise, we found indicators of geographical patterns of thermotolerance as well as relationships between thermotolerance and climate of origin mostly for trees exposed to natural heat. While the origin of provenances partly explained the variation among provenances, acclimation driven by climate played a major role in the response to heat stress. In beech, PSII seems to have a potential for coping with high temperature. [ABSTRACT FROM AUTHOR]

Studies in community genetics have often revealed a relationship between genetic diversity of the focal species and species diversity of the associated biotic communities. This relationship was studied in forest communities dominated by black alder (Alnus glutinosa Gaertn.), one of the few tree species tolerating an anoxic environment of waterlogged soils. It is a dominant species of tree overstory in two types of communities: alder carrs, forest swamps with stagnating water, and riparian forests occurring along smaller waterflows, periodically flooded with a considerable water level fluctuation during the vegetation period. Plant community composition and genetic variation of alder populations were studied in 218 black alder communities of both types distributed along a broad latitudinal transect from the Pannonian lowland to the Western Carpathians (Hungary, Slovakia, Poland). Species diversity was significantly higher in riparian stands than in alder carrs, while no difference was observed in the genetic diversity. The analysis of population structure revealed differentiation between Pannonian and Carpathian populations, which may be attributed to different migration pathways during the Holocene. No correlation was observed between genetic diversity of alder and species diversity of the associated vascular plant communities. On the other hand, using the ddRAD-sequencing approach applied to 96 trees, we identified 19 single-nucleotide polymorphisms significantly associated with climatic and soil variables. However, the hypothesized bioindication function of the plant community composition on the genetic variation of black alder as a focal species was not confirmed. [Display omitted] • Alnus glutinosa forests are specific communities of waterlogged soils – swamps and riparian sites. • There is no link between species diversity of plant community and genetic diversity of the tree layer in alder forests. • Plant species diversity but not tree genetic variation differ between swamps and riparian forests. • Climate, soil and watershed properties determine variation at specific DNA polymorphic sites. [ABSTRACT FROM AUTHOR]

Background and Aims Diversity of the genus Sorbus has been affected by interspecific hybridizations. Pinkflowered hybrid species have been insufficiently studied so far. They comprise bigenomic hybrid species derived from crosses S. aria s.l. × S. chamaemespilus and trigenomic ones, where S. aucuparia was involved as well. The main objective of the present study was to reconstruct their hybrid origins as well as to assess genetic distinction among several morphologically recognized hybrid species. Methods Samples from putative maternal species and eight pink-flowered and two white-flowered hybrid species were collected in the Western Carpathians and the Sudetes. In total, 370 specimens were analysed. Six chloroplast microsatellites were used to infer parentage, whereas nuclear amplified fragment length polymorphism (AFLP) markers were employed for the identification of clones and patterns of genetic variation. Ploidy levels were estimated by flow cytometry on a subset of 140 individuals. Key Results Genetic data supported their hybrid origins proposed based on flower and leaf morphology, and chloroplast DNA (cpDNA) revealed recurrent origins (S. caeruleomontana, S. haljamovae), even from bidirectional hybridization events (S. zuzanae). All bigenomic and trigenomic hybrid species (except triploid S. zuzanae) were found to be tetraploid. In addition to polyploidy, low genetic variation and the presence of clones within and among populations were observed, suggesting predominantly apomictic reproduction of the hybrid species. Most of the described hybrid species appeared also genetically distinct. Conclusions The data suggest that multiple hybridization events in the Western Carpathian Sorbus have led to the formation of separate, partially reproductively isolated genetic lineages, which may or may not be discriminated morphologically. Even bidirectional hybridization can produce individuals classified to the same taxon based on phenotype. For some hybrid taxa, hybridization pathways were proposed based on their genetic proximity to parental species and differences in genome sizes. [ABSTRACT FROM AUTHOR]

Two provenance experiments with Norway spruce in Slovakia were used to reveal trends in the behaviour of provenances after their transfer. Regressions between the average height and survival of provenances and the differences between the geographic and selected climatic characteristics of the place of origin and provenance plots were significant for most of the characteristics tested. Data from the experiment with Polish and Slovak provenances from 1972 indicated that transfer into warmer regions with a longer vegetation period results in improved height growth and survival, with the exception of survival at initial stages. The experiment from 1964 with a broader altitudinal range of provenance plots, but with unadjusted latest measurements at individual plots available, revealed the best height growth of Slovak Norway spruce provenances after their transfer to sites with the mean annual temperature approximately 1°C higher and with the vegetation period 12 days longer than at places of origin. Transfer into lower altitudes, a warmer climate and a longer vegetation period improved survival. In both experiments, transfer to areas with increased rainfall had a negative effect on growth, which is probably associated with the fact that provenances are not able to exploit additional precipitation for the growth in areas with a colder climate and a shorter vegetation period. [ABSTRACT FROM AUTHOR]

• Here, palaeobotanical and genetic data for common beech ( Fagus sylvatica) in Europe are used to evaluate the genetic consequences of long-term survival in refuge areas and postglacial spread. • Four large datasets are presented, including over 400 fossil-pollen sites, 80 plant-macrofossil sites, and 450 and 600 modern beech populations for chloroplast and nuclear markers, respectively. • The largely complementary palaeobotanical and genetic data indicate that: (i) beech survived the last glacial period in multiple refuge areas; (ii) the central European refugia were separated from the Mediterranean refugia; (iii) the Mediterranean refuges did not contribute to the colonization of central and northern Europe; (iv) some populations expanded considerably during the postglacial period, while others experienced only a limited expansion; (v) the mountain chains were not geographical barriers for beech but rather facilitated its diffusion; and (vi) the modern genetic diversity was shaped over multiple glacial–interglacial cycles. • This scenario differs from many recent treatments of tree phylogeography in Europe that largely focus on the last ice age and the postglacial period to interpret genetic structure and argue that the southern peninsulas (Iberian, Italian and Balkan) were the main source areas for trees in central and northern Europe. [ABSTRACT FROM AUTHOR]