Pollen diversity in honeys of the Czech Republic in the 2019 season

Honeybees are important pollinators. As a side product of pollination, honeybees produce honey, as a natural sweetener. The source of honey depends on the hive location. In specific conditions honeybees produce monofloral honey, but more common are polyfloral kinds of honey. In this study honey from the Czech Republic in the 2019 season was evaluated by melissopalynology analysis. The common botanical taxa in the Czech Republic were determined and season impact to pollen taxa was compared for dominant pollen taxa. The taxonomic distribution of pollen in Czech honey was stable during the year. The average number of species was 11.52 taxa per sample. The dominant pollen source in Czech honey was the Brassicaceae family. The high pollen content in honey was confirmed also in the Rosacea family (fruit tree), Ubelliferacae family and Myosotis genus. During the year the pollen taxa were equally distributed in honey. Seasonal effects were confirmed only in Salix genus, Ubelliferacae family and Phacelia genus. Seasonal effects correspond with the blooming season and honeybee handling in the hive was also confirmed. High variability during the season and hive location was confirmed for other taxa.

Tetracycline accumulates in Iberis sempervirens L. through apoplastic transport inducing oxidative stress and growth inhibition

Environmental antibiotic contamination is due mainly to improper and illegal disposal of these molecules that, yet pharmacologically active, are excreted by humans and animals. These compounds contaminate soil, water and plants. Many studies have reported the bioaccumulation of antibiotics in plants and their negative effects on photosynthesis, cell growth and oxidative balance. Therefore, the principal objective of this paper was the study of antibiotic accumulation sites in plants and its uptake modality. Iberis sempervirens L., grown in soil and in agar in the presence or absence of tetracycline, were used as a model system. Using confocal and transmission electron microscopy, we demonstrated that tetracycline was absorbed and propagated in plants through apoplastic transport and also accumulated in intercellular spaces. Tetracycline was rarely detected inside cells (in cytoplasm and mitochondria where, coherent to its pharmacological activity, it probably affected ribosomes), except in stomata. Moreover, we verified and clarified further the phytotoxic effects of tetracycline on plants. We observed that the antibiotic induced a large reduction in plant growth and development and inhibition of photosynthetic activity. As tetracycline may lead to oxidative stress in plants, plant cells tried to balance this disequilibrium by increasing the amount and activity of some endogenous enzyme antioxidant agents (superoxide dismutase 1 and catalase) and levels of antiradical secondary metabolites.