Populations of Heracleum sosnowskyi and H. mantegazzianum (Apiaceae) in Kyiv (Ukraine)

In connection with the increasing negative impact of invasive alien species on biodiversity and the environment in general, their research, as well as throughout the world, is relevant. The distribution of the Heracleum sosnowskyi and H. mantegazzianum of the secondary range on the example of the Kyiv agglomeration is investigated in the work. In our study we aimed to evaluate the possibility of spontaneous spread of giant hogweeds in the secondary range, adaptation of the species to the new conditions of the environment that favor to control of these species’ expansion and reduce the threat to the urban ecosystems and citizens’ health. We hypothesise that in the secondary range H. sosnowskyi and H. mantegazzianum settle sites with relatively high temperature (Tr), lightening (Lc), and soil moisture conditions similar to that in their natural range. 17 populations and four localities (sites) of H. sosnowskyi and H. mantegazzianum were studied. They were found within forest, meadow, riverine and ruderal plant communities. It is indicated that the advent species fully adapted to the conditions of the environment. The difference by ecological indicators Lc2 and Tm1 is pointed out. According to the results of our research, for the area of Kyiv urban agglomeration the growth of H. sosnowskyi and H. mantegazzianum is indicated in the plants communities of six classes. They spread most in ruderal plant communities of the: Robinietea, Artemisietea, Epilobietea classes. The studied species belong to invasive plant species in Ukraine and are characterized by extremely high effect on the environment and high invasive potential.

Chromosome-level assemblies of multiple Arabidopsis genomes reveal hotspots of rearrangements with altered evolutionary dynamics

We report chromosome-level, reference-quality assemblies of seven Arabidopsis thaliana accessions selected across the global range of this predominately ruderal plant. Each genome revealed between 13-17 Mb rearranged and 5-6 Mb novel sequence introducing copy-number changes in ∼5,000 genes, including ∼1,900 genes which are not part of the current reference annotation. Analyzing the collinearity between the genomes revealed ∼350 regions (4.1% of the euchromatin) where accession-specific tandem duplications destroyed the syntenic gene order between the genomes. These hotspots of rearrangements were characterized by the loss of meiotic recombination in hybrids within these regions and the enrichment of genes implicated in biotic stress response. Together this suggests that hotspots of rearrangements are governed by altered evolutionary dynamics as compared to the rest of the genome, which are based on new mutations and not on the recombination of existing variation, and thereby enable a quick response to the ever-evolving challenges of biotic stress.

First record of Solidago × Snarskisii (Asteraceae) in Poland

Pliszko A., 2018: First record of Solidago ×snarskisii (Asteraceae) in Poland. - Botanica, 24(2): 211-213. The paper deals with Solidago ×snarskisii, a natural hybrid between the North American S. gigantea and the European S. virgaurea, as a new casual alien species to the flora of Poland. It was found in August 2018 in the town of Suwałki, NE Poland, growing on a fallow land among its parental species. The population of the hybrid consisted of one cluster of shoots, including four generative and three vegetative shoots, and it was associated with meadow, grassland, and ruderal plant species. The locality of S. ×snarskisii in Poland was mapped using the ATPOL cartogram method.