Cell wall components, especially arabinogalactan proteins (AGPs) and pectins as the source of signaling molecules active in cell-to-cell communication, are involved in many biological processes, including plant growth and development. Understanding the mechanisms of intercellular communication is particularly important in the context of reprogramming cell fate and transition from somatic to germline identity. The present study focuses on immunodetection of some pectic epitopes and AGPs in young ovules of selected Hieracium, Pilosella and Taraxacum species. The purpose of this research was to answer the questions: (1) whether the distribution of pectins and AGPs is related to the mode of reproduction and (2) whether their spatial and temporal distribution in young ovules may herald a later differentiation of the nutrient tissue present in the integument of mature ovules. We analyzed the localization of low and highly methyl-esterified pectins and AGP epitopes using monoclonal antibodies, i.e., LM19, LM20, JIM13, respectively. Our research found no significant differences in the localization of pectins and AGPs in young ovules of sexual and apomictic species, and the initial distribution pattern of these compounds did not appear to be related to the subsequent differentiation of the periendothelial nutrient zone. The presented findings may confirm the existence of a general developmental trend in the spatial and temporal distribution of pectins and AGPs during the maturation of ovules in angiosperms.

Taraxacum Officinale, commonly called dandelion, is herbaceous perennial belonging to the family of Asteraceae, having good antibacterial effects which are related to its phenolic substances. In this study, the effect of phenolic contents as well as the antibiofilm activity against Staphylococcus aureus of phenolic extract from T. Officinale were evaluated in vitro. With 70% metha- nol-water (v/v) as a solvent, the dandelion was extracted by ultrasonic assisted extraction method. Subsequent identification and quantification of phenol in extract was carried out using High Performance Liquid Chromatography (HPLC). The minimum inhibitory concentration and anti- bacterial kinetic curve of dandelion phenolic extract were analyzed by spectrophotometry. Changes in extracellular alkaline phosphatase (AKP) contents, electrical conductivity, intracellular protein contents, and DNA of S. aureus after the action of dandelion phenolic extract were determined to study its effect on the permeability of S. aureus cell wall and cell membrane. The results showed that chlorogenic acid (1.34 mg/g) was present in higher concentration, followed by luteolin (1.08 mg/g), ferulic acid (0.22 mg/g), caffeic acid (0.21 mg/g), and rutin (0.19 mg/g) in the dandelion phenolic extract. The minimum inhibitory concentration (MIC) of dandelion phenolic extract against S. aureus was 12.5 mg/mL. The antibacterial kinetic curve analysis showed that the inhibitory effect of dandelion phenolic extract on S. aureus was mainly in the exponential growth phase. After applying the dandelion phenolic extract, the growth of S. aureus was signifi- cantly inhibited entering into the decay phase early. Furthermore, after the action of dandelion, the extracellular AKP contents of S. aureus, the electrical conductivity and the extracellular protein contents were all increased. The phenolic extract also affected the normal reproduction of S. aureus. These results suggest that dandelion has an inhibitory effect on S. aureus, and the mechanism of its action was to destroy the integrity of the cell walls and cell membranes.

The paper reports a comparative study of the female gametophyte and especially synergid structure in sexual and apomictic dandelions. We analyzed diploid sexually reproducing Taraxacum linearisquameum (2n = 2x = 16) and two triploids, T. alatum and T. udum (2n = 3x =24), with autonomous embryo and endosperm development. There were no observed differences in the organization of the mature megagametophyte between the examined species. Both meiotically reduced and diplosporous embryo sacs showed typical polarity of the egg apparatus cells, together with development of a filiform apparatus in the synergids, but immunocytochemical analyses indicated that microtubules form longitudinal brush-like bundles adjacent to the filiform apparatus in the synergids of the sexual T. linearisquameum. This arrangement of cytoskeletal elements is similar to the configuration described in other amphimictic plants. The synergids of the apomictic T. alatum and T. udum show a uncharacteristic and relatively weak cytoskeleton with no brush-like bundles. We discuss the role of synergids in autonomous apomicts.

Somatic chromosome numbers are given for the following Taraxacum species: T. pieninicum, 2n=16; T. dentatum, 2n=24; T. fascinans, 2n=24; T. mendax, 2n=40; T. subalpinum, 2n=24; T. telmatophilum, 2n=24; T. cyanolepis, 2n=24; T. fulgidum, 2n=24; T. gentile, 2n=24; and T. undulatum, 2n=24. Chromosome numbers from Poland are published for the first time for T. dentatum, T. fascinans, T. mendax, T. subalpinum, T. telmatophilum, T. cyanolepis, T. fulgidum, T. gentile and T. undulatum.

An efficient micropropagation system for Taraxacum pieninicum using seedling explants germinated in vitro is described. Shoot tips and fragments of cotyledons, hypocotyls and roots were isolated from several-day-old seedlings. The highest response, 100% frequency with 12.3 axillary shoots/explant, was from shoot tips on medium supplemented with 0.5 mg L-1 BA and 0.05 mg L-1 NAA. In subsequent subcultures the number of shoots was significantly higher on all explants cultured on medium containing 0.25 and 0.5 mg L-1 BA, and the multiplication rate was highest (20 shoots/explant) in the 4th passage. Shoots rooted on MS and 1/2 MS medium; the highest rooting frequency was 90% and the highest number of roots 2.7/shoot. Rooted plants showed 96.2% survival in sterile soil:sand, and 100% survival in hydroponic culture. Regenerated plants flowered in the second year after acclimatization and yielded viable seeds. This protocol for obtaining complete plants through micropropagation may prove useful for conservation of the genetic resources of this and other endangered species

The eastern area of Poland is the land of great natural worth both on a country and Europe's scale. This area encompasses the valley of the middle-Bug river that is preserved as the Landscape Park. In this research an attempt was undertaken to assess the heavy metal pollution of the environment in the area of the Landscape Park named ,,The Podlasie Ravine of the Bug River". The level of heavy metals in falling dust, soil, and Dandelion (Taraxacum ojficinale Webb.) was being examined in the five localities, situated in the area of the Park. The research showed that none of the mean permissible standard values of the falling dust, Pb, and Cd were outreached; however, it was observed that the fall of Pb was locally higher in relation to the standard Pb fall values in Janów Podlaski. The concentration level of the elements in the soil equaled the ,,O" degree of heavy metal pollution of the soils. In the circumstances of the reaction soil about pH 6- 7 and low concentrations of the metals in the soil the Cd, Pb elements accumulate in Dandelion in trace quantities. The obtained results indicate that there is no threat whatsoever existing in the shape of the heavy metals in the area of the Landscape Park ,,The Podlasie Ravine of the Bug River".