The aim of the present work was to examine the role of UV-C irradiation on the production of secondary metabolites (total phenolic, total flavanols, total flavonols, catechin, ferulic acid and trans-resveratrol in phenolic compounds and α-, β-, γ- δ-tocopherols) in callus cultures. Studies on the effects of UV-C treatment on callus culture are seldom and generally focused on UV-B. However UV-C radiation play an important role in accumule secondary metabolites. In this study, callus cultures from Öküzgözü grape cultivar were initiated from leaf petiole explants. Calli formed after 6 weeks on the medium supplemented with 0.5 mg L-1 benzylaminopurine (BA), 0.5 mg L-1 indole acetic acid (IAA) on B5 media. Callus tissues were exposed to UV-C irradiation at 10, 20 and 30 cm distances from the UV source for 5 and 10 minutes and samples were collected at hours 0, 24 and 48. The greatest total phenolic content (155.14 mg 100 g-1) was detected in calli exposed to UV-C for 5 min from 30 cm distance and sampled after 24 h. 24 h and 48 h incubation times, 30 cm and 5 min were the most appropriate combination of UV-C application in total flavanol content. Maximum total flavonol content (7.12 mg 100 g-1) was obtained on 0 h, 5 min and 20 cm combination. The highest (+)- catechin accumulation (8.89 mg g-1) was found in calli with 10 min UV-C application from 30 cm distance and sampled after 48 h. Ferulic acid content increased 6 fold in Öküzgözü callus cultures (31.37 μg g-1) compared to the control group. The greatest trans-resveratrol content (8.43 μg g-1) was detected in calli exposed to UV-C for 5 min from 30 cm distance and sampled after 24 h. The highest α-tocopherol concentration was found in calli exposed to UV-C for 10 min from 30 cm distance and sampled after 24 h. As a conclusion, it was showed that UV-C radiation had remarkable promoting effects on the accumulation of secondary metabolites in the calli of Öküzgözü grape cultivar.

Plant secondary metabolites are possess several biological activities such as anti-mutagenic, anti-carcinogenic, anti-aging, etc. Cell suspension culture is one of the most effective systems to produce secondary metabolites. It is possible to increase the phenolic compounds and tocopherols by using cell suspensions. Studies on tocopherols production by cell suspension cultures are seldom and generally focused on seed oil plants. Although fresh grape, grape seed, pomace and grape seed oil had tocopherols, with our best knowledge, there is no research on tocopherol accumulation in the grape cell suspension cultures. In this study, it was aimed to determine the effects of cadmium chloride treatments on secondary metabolite production in cell suspension cultures of grapevine. Cell suspensions initiated from callus belonging to petiole tissue was used as a plant material. Cadmium chloride was applied to cell suspension cultures in different concentration (1.0 mM and 1.5 mM) to enhance secondary metabolite (total phenolics, total flavanols, total flavonols, trans-resveratrol, and α-, β-, γ- δ-tocopherols) production. Cells were harvested at two days intervals until the 6th day of cultures. Amounts of total phenolics, total flavanols and total flavonols; trans-resveratrol and tocopherols (α-, β-, γ- and δ-tocopherols) and dry cell weights were determined in the harvested cells. Phenolic contents were significantly affected by the sampling time and cadmium concentrations. The highest values of total phenolic (168.82 mg/100 g), total flavanol (15.94 mg/100 g), total flavonol (14.73 mg/100 g) and trans-resveratrol (490.76 μg/100 g) were found in cells treated with 1.0 mM CdCl2 and harvested at day 2. Contents of tocopherols in the cells cultured in the presence of 1.0 mM CdCl2 gradually increased during the culture period and the highest values of α, β and γ tocopherols (145.61, 25.52 and 18.56 μg/100 g) were detected in the cell cultures collected at day 6. As a conclusion, secondary metabolite contents were increased by cadmium chloride application and sampling time, while dry cell weights was reduced by cadmium chloride treatments.

Plants play an essential role in the ecological cycle; however, they face numerous global biotic and abiotic stress factors. The capacity of plants to survive in adverse conditions is called stress tolerance. Drought stress is among the major stresses faced by plants, as arid conditions affect plant development and productivity, crop yield, relative water content, nutrient intake, photosynthesis, dry matter accumulation, and respiration. Hormones play an essential role in plant stress metabolism. Until recently, it was thought that plant hormones consisted of five groups: auxin, gibberellin, cytokinin, abscisic acid, and ethylene. However, other substances synthesized by plants, such as jasmonates, brassinosteroids, salicylic acid, and nitric oxide, have also shown critical vital functions in the plant, like the hormones. Another hormone in these substances is strigolactone (SL), which has been reported to perform essential functions in stress physiology. This research investigated the effects of SL applications on drought stress on 1103 Paulsen American Grapevine Rootstock. GR24, a synthetic analog of SLs, was applied to grapevine rootstock. Physical and biochemical changes were determined (chlorophyll, membrane injurity, prolin, lipid peroxidation, soluble protein, superoxide dismutase, ascorbate peroxidase activities, phenolic compounds, plant hormones, and mineral elements). The results show that GR24 applications effectively alleviate the harmful effects of drought stress in most features.

This research was carried out to investigate the effects of chemical mutagen applications on producing phenolic compounds in calli obtained from leaf petiole explants of the Royal grape variety.Petioles were cultured in B5 medium containing 0.5 mg/L benzyl amino purine and 0.5 mg/L indole acetic acid to obtain callus. Calli obtained during the period following planting were subcultured in the same culture conditions three times at one month intervals. In the fourth subculture, the calli were transferred to nutrient mediums with the same composition containing ethyl methanesulfonate, sodium azide, azacitidine and acridine orange in three different doses, 0.5 mM, 1.0 mM, and 2.0 mM, and cultured in these mediums for 60, 120 and 180 minutes. Then, they were cultured again for four weeks in mutagen-free nutrient mediums with the same content as their previous mediums. At the end of this period, calli were taken from their nutrient medium, and total phenolic compound, total flavanol, total flavonol and anthocyanin analyzes were performed.As a result of the research, it has been determined that all mutagens applied are effective in increasing the production of phenolic compounds depending on the dose and time.