• Energy Research

Sages and their beneficial secondary metabolites have been used in conventional and traditional medicine in many countries, and are extensively studied for their health effects. However, to achieve high production levels, it is crucial to optimize the cultivation conditions. The aim of our study was to determine the optimal light-emitting diode (LED) treatment strategy for promoting plant growth and polyphenol biosynthesis in S. atropatana and S. bulleyana in vitro cultures. Shoots of both species were grown under red, blue, mixed (70 % red and 30 % blue), or white (control) light. The lighting conditions affected not only culture growth and proliferation potential, but also the accumulation of polyphenols and the expression of the genes involved in their biosynthesis (PAL, TAT, RAS). The highest proliferation rates (6.21 for S. atropatana and 4.26 for S. bulleyana) were achieved under white LEDs. In contrast, the highest biomass production was observed under white and mixed red/blue light (both species), although a similar effect was revealed for the blue light treatment for S. bulleyana. The dominant polyphenol in both species was rosmarinic acid: its level was highest in S. atropatana shoots exposed to red light (20.86 mg/g dry weight, DW) and S. bulleyana under white light (19.72 mg/g DW). The effects of the light treatments on gene expression varied between plant species and the analyzed gene; for example, mixed light stimulated RAS expression in S. bulleyana shoots and inhibited it in S. atropatana shoots. Principal component analysis found that gene expression did not always translate directly into rosmarinic acid production. In summary, our findings indicate that optimized lighting conditions have a significant effect on the production of polyphenolic compounds in sage shoot cultures. However, further research is needed to find the relationship between light treatment and plant biosynthetic pathway.

Plants of the Clerodendrum genus, known for their rich phytochemical profiles, are used in traditional Chinese, Korean, Japanese, and Indian medicine to treat various ailments, including inflammation, hypertension, diabetes, hyperlipidemia, and cancer. Due to the limited natural availability of these plants, there is a growing interest in utilizing in vitro culture techniques to produce their bioactive compounds sustainably. In this study, the effects are compared of Murashige and Skoog (MS), Woody Plant medium (WP), Gamborg B5 (B5), and Schenk and Hildebrandt (SH) basal media on growth, biomass accumulation, and polyphenolic compound production in shoot cultures of Clerodendrum colebrookianum and Clerodendrum trichotomum. The composition of the culture medium significantly influenced the growth and metabolic profiles of both species. C. trichotomum exhibited the highest proliferation potential on WP and SH media, while C. colebrookianum was similar on WP, SH, and B5 media (multiplication factor of about 20). Dry weight accumulation was highest in C. trichotomum grown on SH medium (0.292 g/culture), while C. colebrookianum achieved a comparable biomass on SH and WP media (0.240 g/culture and 0.228 g/culture, respectively). The chemical analysis showed similar secondary metabolite profiles between the two Clerodendrum species with phenylethanoids such as acteoside being the predominant bioactive compounds in hydromethanolic extracts. WP medium was the most favorable for polyphenol accumulation in C. colebrookianum (64.5 mg/g DW), while the SH medium yielded the highest total polyphenol content in C. trichotomum (36.6 mg/g DW). In this study, the importance is underscored of basal medium selection in optimizing the in vitro production of bioactive polyphenolic compounds in Clerodendrum species, providing a foundation for the sustainable and scalable production of these pharmacologically significant metabolites.

Salvia bulleyana is a plant native to the Chinese Yunnan Province. This species has been used in traditional Chinese medicine as a substitute for Danshen (the roots of Salvia miltiorrhiza). The aim of our study was to establish an effective system for propagating S. bulleyana shoots to obtain large amounts of material rich in bioactive compounds. Phytohormones were used to regulate shoot growth and regeneration potential and influence plant secondary metabolism. The shoot tips were incubated on a Murashige and Skoog agar medium supplemented with 0.1 or 0.5 mg/L IAA (indole-3-acetic acid) and the cytokinins benzylaminopurine (BAP), meta-topoline (M-T), 6-benzylaminopurine riboside (RBAP), N-benzyl-9-(2-tetrahydropyranyl)-adenine (BPA) or kinetin, (K) at concentrations of 0.5, 1 or 2 mg/L. It was observed that the type and concentration of growth regulator significantly influenced the regeneration potential of S. bulleyana shoots. The highest multiplication rate was obtained when 0.1 mg/L IAA and 2 mg/L BPA were used. Under these conditions, 100% of shoot tips formed buds and almost seven buds/shoot per explant were obtained after five weeks. Meanwhile, the highest biomass was found for shoots growing on a medium supplemented with 0.1 mg/L IAA and 1 mg/L M-T: 1.2 g of fresh weight and 0.17 g of dry weight. However, a medium with 0.1 mg/L IAA and 2 mg/L RBAP was most favorable for bioactive phenolic acid content, with a total polyphenol level (37.7 mg/g dw) 4.5 times higher than in shoots grown on medium without growth regulators (8.23 mg/g dw). Finally, optimal conditions were selected by TOPSIS (technique for order of preference by similarity to the ideal solution); the culture of S. bulleyana grown on an MS medium containing 0.1 mg/L IAA and 1 mg/L M-T was found to be the most efficient for polyphenol accumulation and can be used for the production of medicinally relevant compounds.

This study reports the first successful establishment of Perovskia atriplicifolia hairy root cultures using Rhizobium rhizogenes and evaluates their potential for bioactive phenolic acid production, particularly rosmarinic acid (RA). Hairy roots were induced using two R. rhizogenes strains, A4 and ATCC 15834; transformation was confirmed by PCR analysis targeting the rol and aux genes. The A4 strain exhibited higher transformation efficiency (41.3%) than ATCC 15834 (30.2%). Eight transgenic root clones (C1–C8) were established and confirmed as transformed. The clones exhibited significant variation in biomass accumulation and phenolic acid production. RA production was most strongly correlated with PAL, RAS, and CYP98A14 expression. Hierarchical clustering clustered the clones into three groups based on growth, metabolite content, and gene expression. Lines C1 and C2 exhibiting the highest RA, total polyphenol content, and the highest productivity were selected for further experiments. McCown Woody Plant (WP) and Schenk and Hildebrandt (SH) media demonstrated the greatest biomass accumulation, with growth indexes exceeding 13. Conversely, Gamborg (B5) medium enhanced RA content, achieving 38.3 and 40.8 mg/g dry weight (DW) for clones C1 and C2, respectively, representing a fourfold increase compared to the least favorable Murashige and Skoog (MS) medium. These findings establish P. atriplicifolia hairy roots as efficient systems for RA biosynthesis and can provide a basis for metabolic engineering and scale-up production of phenolic acids in medicinal plants.