Tadeusz Czuj

Tocopherols are essential lipid-soluble antioxidants that play important roles in plant protection against oxidative stress and are closely connected with isoprenoid metabolism. To the best of our knowledge, this is the first report of stable constitutive expression of Arabidopsis thaliana VTE2 (AtVTE2) in flax (Linum usitatissimum L.) and its effects on plant metabolism and development. As a dual-purpose oil and fibre crop, flax combines PUFA-rich seeds with industrially important fibre-rich stems, providing a useful system for assessing the broader consequences of antioxidant-pathway engineering. Three independent transgenic lines were characterized by RT-qPCR analysis of genes associated with tocopherol, MEP, MVA, and carotenoid biosynthesis, targeted metabolite profiling, antioxidant-capacity assays, field phenotyping, and biochemical and spectroscopic analyses of mature straw. Three independent transgenic lines were characterized using gene-expression analyses, metabolic profiling, antioxidant assays, phenotypic evaluation, and biochemical analyses of mature stems. Constitutive AtVTE2 expression was associated with α-tocopherol accumulation and was accompanied by coordinated transcriptional changes in genes associated with the plastidial methylerythritol phosphate and cytosolic mevalonate pathways. These changes were associated with modifications in isoprenoid and phenylpropanoid metabolism, enhanced antioxidant capacity in selected transgenic lines, and altered plant architecture under field conditions. In mature straw, transgenic plants exhibited changes in phytosterol composition, lignin accumulation, and pectin distribution, whereas cellulose content remained unchanged. FT-IR spectra retained the same principal bands but showed differences in the relative intensities of selected cell-wall-associated bands. Collectively, these findings demonstrate that constitutive AtVTE2 expression is associated with tissue-dependent metabolic responses extending beyond vitamin E accumulation and affecting interconnected pathways involved in secondary metabolism, antioxidant capacity, and cell-wall organization.

The aim of the present study was to evaluate the morphogenetic efficiency of the new flax (Linum usitatissimum L.) cultivar Silesia. The plant material consisted of five ecotypes of Silesia seeds selected by determining the fatty acid composition in individual plants. Thus, five ecotypes with different fatty acid compositions were applied for germination, and the resulting seedlings were used for callus induction. The observed in vitro morphogenic response of explants to the used callus induction medium was 100%, followed by varying development of shoots, with the highest value being 17 shoots per callus, with an average length of 7.15 cm (for ecotype 1). The biochemical analyses showed photosynthetic pigments were significantly affected by the tested ecotypes. The main conclusion is that the selection of plant material as a source of tissue cultures is crucial for efficient regeneration and organogenesis. One factor potentially influencing these processes is fatty acid composition and the ratio of linoleic to α-linolenic acid. A ratio ranging from 1.36 to 1.68 in the source material (seeds) used for initiation of tissue cultures resulted in the highest efficiency of shoot regeneration and number of obtained shoots per callus. A strong negative correlation (−0.78) was observed between shoot regeneration efficiency and the ratio of linoleic to α-linolenic acid in seeds from which the explants were obtained. Moreover, an efficient protocol of micropropagation from callus tissue was established for the new flax cultivar Silesia. An interesting insight into the metabolism of the obtained regenerants allowed us to determine the relationship between the content of chlorophyll and rhizogenesis efficiency. For these two parameters, the calculated correlation coefficient was 0.66. A strong relationship (high correlation coefficient: 0.79) was also established between flavonoid content and length of obtained regenerants, pointing to the developmental role of flavonoids.