Background/Objectives: Essential oils of Thymbra spicata subsp. spicata are known for their rich phytochemical content and bioactive properties. This study aimed to evaluate the antimicrobial, anti-biofilm and anti-quorum sensing, as well as the cytotoxic activities of T. spicata subsp. spicata essential oils (TS-EO1 and TS-EO2) obtained from two different localities in Türkiye, along with a detailed chemical composition analysis. Methods: TS-EO1 and TS-EO2 were obtained by the hydrodistillation method and analyzed using Gas Chromatography—Mass Spectrometry (GC-MS) to determine their phytochemical profiles. Antimicrobial activities were assessed against Gram-positive and Gram-negative bacteria, and fungal strains were assessed using the broth microdilution method. Anti-biofilm and anti-quorum sensing activities were evaluated using Pseudomonas aeruginosa PAO1 and Chromobacterium violaceum ATCC 12472, respectively. Cytotoxic properties were tested on four cell lines (A549, MCF-7, U87MG, and L929) using the MTT assay. Results: Both essential oil samples were rich in carvacrol (54.3% and 54.1%), followed by p-cymene and γ-terpinene. The essential oils exhibited significant antimicrobial activity, particularly against Staphylococcus aureus (6.25 mg/mL) and Candida parapsilosis (0.20 mg/mL). Sub-MIC concentrations significantly inhibited biofilm formation and quorum sensing. Both samples showed moderate cytotoxic properties against human cancer cell lines, particularly A549 (IC50: 116.3 and 134.4 μg/mL, respectively). Conclusions: This study showed that T. spicata subsp. spicata essential oils have significant antimicrobial, anti-biofilm, and anti-quorum sensing properties against various bacteria and fungi, along with moderate cytotoxic effects, indicating their medicinal and pharmaceutical potentials. This is the first study which revealed anti-biofilm and anti-quorum sensing properties of T. spicata essential oils to our knowledge.

In this study, the effects of exogenous silicon dioxide applications (0.5, 1, 1.5 mM SiO2) on the germination parameters of carrot seeds were investigated under salt stress conditions (150, 200 mM NaCl). For this purpose, germination percentage (GP), mean germination time (MGT), germination rate coefficient (CVG), germination rate index (GRI), germination index (GI), seedling viability index (SVI), leaf number, shoot and root lengths (mm) and plant fresh weight (g) were determined. Germination parameters of yellow carrot, sensitive to salt stress, were adversely affected by 150 mM NaCl application and shoot and root lengths were reduced by 80%. Especially SiO2 applications had a positive effect on germination parameters for the cultivar. In 150 mM NaCl application, the germination of the seeds treated with 0.5 mM SiO2 increased approximately two times (23%), and 15% germination was obtained in 200 mM NaCl, which did not germinate in the control. Although the black carrot cultivar tolerated salt stress, silicon dioxide treatments had a stimulating effect on germination and development. It was determined that especially 1.5 mM SiO2 application in black carrot seeds had a positive effect on germination parameters. Germination percentage increased to 93% in seeds treated with 1.5 mM SiO2 in 150 mM NaCl, and 86% at 200 mM NaCl concentration, reaching higher values compared to the control group. The results showed that pre-treatment with appropriate silicon concentrations significantly improved germination performance and promoted tolerance to the salt stress.

Gypsophila pilulifera Boiss. & Heldr., an endemic and endangered species is an economically important plant that has a potential used in medicine thank to the saponins it contains. It is also an ornamental plant. In this study, the production was carried out under in vitro conditions in order to protect and economically evaluate the species, which is in danger of extinction due to its distribution in a very narrow area open to anthropogenic effects. For this purpose, seed and shoot tip explants of G. pilulifera were cultured in Murashige and Skoog (MS) medium containing different concentrations of 6-benzylaminopurine (BAP), indole-3-acetic acid (IAA) and naphthaleneacetic acid (NAA). Explants were obtained from two different locations of the natural habitats of G. pilulifera and more plants were obtained in the tissue culture from both explant types taken from the 1st location. Propagation from seed gave better results, and 96.67% of the seeds cultured in hormone-free MS medium were germinated and rooted. The shoot tip showed lower regeneration in vitro than the seed explant. Especially the rooting percentage is quite low and the highest rooting and shoot formation was obtained in MS medium containing 2 mg/L BAP + 2 mg/L IAA. In this medium, 10.50 ±0.17 shoots were obtained per plant, and rooting (1.67 ±0.09 per plant) was also achieved only in this medium. Seedlings obtained in tissue culture continue to develop successfully in field conditions, and this method has been determined as a suitable method for ex-situ conservation and economically rapid production of the species.

Background/Objectives: The aim of the present study was to evaluate the antimicrobial, antibiofilm, anti-quorum sensing, and cytotoxic activities of the essential oils extracted from the leaves of Dorystoechas hastata Boiss & Helder. ex Bentham (Lamiaceae) (DHL-EO) as well as to determine the chemical composition of the essential oils obtained from both the leaves and roots. Methods: The essential oils of the root and leaf were extracted by the hydrodistillation method. The chemical composition of the two oils was determined by Gas Chromatography–Mass Spectrometry (GC-MS). The antimicrobial activity of DHL-EO was determined against Gram-positive, Gram-negative bacteria, and various Candida species using the broth microdilution method. Pseudomonas aeruginosa PAO1 and Chromobacterium violaceum ATCC 12472 were used for antibiofilm and anti-quorum sensing activities, respectively. The cytotoxic activity of the DHL-EO was examined by MTT assay. Results: Eucalyptol (21.3%), 2-bornanone (17.0%), and α-pinene (10.3%) were the main compounds of the DHL-EO. The root essential oil (DHR-EO) had trans-ferruginol (19.2%), guaiol (14.1%), and ar-abietatriene (14.0%) as the main components. The DHL-EO displayed weak and moderate antimicrobial activity. The DHL-EO showed moderate antibacterial activity against Staphylococcus aureus ATCC 29213 (methicillin-susceptible, MSSA) and S. aureus ATCC 43300 (methicillin-resistant, MRSA), with a MIC value of 12.5 mg/mL. The DHL-EO exhibited the strongest antifungal activity against Candida parapsilosis RSKK 994, with a MIC value of 0.78 mg/mL. It also demonstrated antifungal activity against C. parapsilosis ATCC 22019 and Candida krusei RSKK 3016, with MIC values of 3.12 mg/mL. The DHL-EO showed antibiofilm activity in a concentration-dependent manner, particularly at higher concentrations, and inhibited violacein production in a dose-dependent manner, with anti-quorum sensing activity. The DHL-EO displayed moderate cytotoxic activity against MCF-7 (IC₅₀: 110.3 μg/mL) and A549 (IC₅₀: 120.4 μg/mL) cell lines. Conclusions: The chemical composition of DHL-EO and DHR-EO showed qualitative and quantitative differences from each other in the present study. The essential oil of the leaves showed moderate cytotoxic and antibacterial activities.

Gypsophila pilulifera Boiss. & Heldr. is an economically important critically endangered (CR) endemic species of Turkey. This species is a Mediterranean element and type sample is located in square C3 (Antalya). Plants are much more sensitive to abiotic stress factors, especially during germination and seedling development stages. In this study, in vitro germination and seedling growth properties of G. pilulifera Boiss. & Heldr. (Caryophyllaceae) were investigated under salt and drought stress. The seeds were cultured in hormone-free MS media containing increasing doses of NaCl (50, 100, 150, 200 mM) and PEG 6000 (5%, 10%, 15% and 20%). Germinated seeds were counted every three days for the first week and every day for the second week. The root and hypocotyl length, number of leaves, fresh weight and vigor index of the plants were determined at the end of 21 days. A negative correlation was determined between increased salt and drought stress and all vegetative growth parameters. Although germination was obtained on MS medium with the highest level of drought (20%), there was no germination on MS medium containing 200 mM NaCl. As a result, it was determined that the plant was more sensitive to salinity stress than drought and high salt concentrations inhibited the germination by 100%.

A detailed study of the Turkish endemic Gypsophila pilulifera were presented by both morphological and molecular investigations of several sites (each one divided in four biotopes). The characteristics were investigated using statistic analyses, i.e. t-Test and One-way ANOVA tests, as well as Discriminant analysis (á=0.05). Some differences were detected among the individuals in the locations stufied where the species was distributed in terms of morphological characteristics and obvious similarities/differences were determined among the biotopes as a result of the discriminant analysis. Morphological characterization was supported by molecular data. Four individuals from two different locations were analyzed by PCR using twenty-four ISSR primers. Analysis of PCR products on agarose gel yielded three primary reproductive band profiles, and the similarity frequencies calculated with the Jaccard coefficient were found to be among 0.229 and 0.769. In this context, according to the results, there was no difference in species, subspecies or variety level between individuals between the two locations. But the obtained molecular differences support the morphological differences. It is predicted that this may change towards speciation as ecological changes increase in the locations where the species is distributed.