Lignans, as secondary metabolites synthesized within a phenylpropanoid pathway, play various roles in plants, including their involvement in growth and plant defense processes. The health and nutritional benefits of lignans are unquestionable, and many studies have been devoted to these attributes. Although the regulatory role of miRNAs in the biosynthesis of secondary metabolites has been widely reported, there is no systematic review available on the miRNA-based regulatory mechanism of lignans biosynthesis. However, the genetic background of lignan biosynthesis in plants is well characterized. We attempted to put together a regulatory mosaic based on current knowledge describing miRNA-mediated regulation of genes, enzymes, or transcription factors involved in this biosynthesis process. At the same time, we would like to underline the fact that further research is necessary to improve our understanding of the miRNAs regulating plant lignan biosynthesis by exploitation of current approaches for functional identification of miRNAs.

Some seeds of flowering plants can differentiate their seed coat epidermis into the specialized cell layer producing a hydrophilic mucilage with several ecological functions, such as seed hydration, protection, spatial fixation, stimulation of metabolic activity and development of seed. Due to the species- and genotype-dependent variabilities in the chemical composition of mucilage, mucilage does not display the same functional properties and its role depends on the respective species and environment. Mucilaginous substances, depending on their composition, exhibit many preventive and curative effects for human and animal health, which has significant potential in the agricultural, food, cosmetic and pharmaceutical industries. This paper summarizes the ecological, biological, and functional properties of mucilaginous plant substances and highlights their significant nutritional potential in terms of the development of functional foods, and nutraceuticals and dietary supplements. A paragraph describing the gene regulation of seed mucilage synthesis is included, and some recommendations for the direction of further research on mucilaginous substances are outlined.

The significant healing effect of Tilia platyphyllos Scop. and Tilia cordata Mill. flowers are well known. However, the flowers of Tilia tomentosa Moench. are not suitable for harvest due to their toxic effects. To investigate the diverse background of this effect, we applied a functional miRNA-based marker, mannose expression analysis and determined the content of bioactive compounds. Out of nine tested markers, three (miR160, miR167 and miR408) provided reproducible miRNA-based loci and two of them (miR160 and miR398) enabled the acquisition of fingerprinting specific to flower and leaf samples of T. platyphyllos and T. tomentosa. The most pronounced profiling was specific for miR408 marker, the function of which is connected to plant defense and adaptation mechanisms. We confirmed the suitability of microRNA-based markers for polymorphism determination of flowers of selected species of lime-tree. The highest values of antioxidant activity, flavonoids, total polyphenols and phenolic acids content have been reached in silver linden flowers. When comparing the transcription activity of mannose in flowers, more than 30 times higher levels of mannose transcripts for the silver linden flowers was observed.

Aesculus hippocastanum L. ˈBaumaniiˈ (syn.: A. hippocastanum L. ˈFlore Plenoˈ; A. hippocastanum ˈPlenaˈ) is a rarely cultivated cultivar characterized by fully white and sterile flowers, and as a result it does not produce fruit. For identification and characterization of the morphological, molecular, and biochemical parameters of this cultivar, we performed the pollen viability test, morphological analysis of flowers, assay of miRNA-based markers and biochemical analyses. The results show that the germination of pollen grains in artificial media reached 0 % and the pistil in flowers was undeveloped. The antioxidant activity, total polyphenol and flavonoid content exhibited the highest values of all three tested parameters (1.5540 mg TEAC/g FM; 3.7278 mg GAE/g FM and 1.328 mg CAE/g FM) in the extracts from A. hippocastanum ˈBaumaniiˈ. The applied miRNA-based markers showed a sample-specific and tissue-specific genomic polymorphism. Various DNA fingerprinting profiles between the flowers and leaf samples of fruiting and barren trees were noted. URL: https://www.upjs.sk/pracoviska/botanicka-zahrada/odborne-aktivity/contents-abstracts/