UV-C mediated accumulation of pharmacologically significant phytochemicals under light regimes in in vitro culture of Fagonia indica (L.).

Fagonia indica (L.) is an important medicinal plant with multitude of therapeutic potentials. Such application has been attributed to the presence of various pharmacological important phytochemicals. However, the inadequate biosynthesis of such metabolites in intact plants has hampered scalable production. Thus, herein, we have established an in vitro based elicitation strategy to enhance such metabolites in callus culture of F. indica. Cultures were exposed to various doses of UV radiation (UV-C) and grown in different photoperiod regimes and their impact was evaluated on biomass accumulation, biosynthesis of phytochemicals along antioxidant expression. Cultures grown under photoperiod (16L/8D h) after exposure to UV-C (5.4 kJ/m2) accumulated optimal biomass (438.3 g/L FW; 16.4 g/L DW), phenolics contents (TPC: 11.8 µgGAE/mg) and flavonoids contents (TFC: 4.05 µgQE/mg). Similarly, HPLC quantification revealed that total production (6.967 µg/mg DW) of phytochemicals wherein kaempferol (1.377 µg/mg DW), apigenin (1.057 µg/mg DW), myricetin (1.022 µg/mg DW) and isorhamnetin (1.022 µg/mg DW) were recorded highly accumulated compounds in cultures at UV-C (5.4 kJ/m2) dose than other UV-C radiations and light regimes.. The antioxidants activities examined as DPPH (92.8%), FRAP (182.3 µM TEAC) and ABTS (489.1 µM TEAC) were also recorded highly expressed by cultures under photoperiod after treatment with UV-C dose 5.4 kJ/m2. Moreover, same cultures also expressed maximum % inhibition towards phospholipase A2 (sPLA2: 35.8%), lipoxygenase (15-LOX: 43.3%) and cyclooxygenases (COX-1: 55.3% and COX-2: 39.9%) with 1.0-, 1.3-, 1.3- and 2.8-fold increased levels as compared with control, respectively. Hence, findings suggest that light and UV can synergistically improve the metabolism of F. indica and could be used to produce such valuable metabolites on commercial scale.

Lead (Pb) bioaccumulation and antioxidative responses in Tetraena qataranse.

Lead (Pb) is the second most toxic metal on Earth and is toxic to humans and other living things. In plants, Pb commonly inhibits growth when it is at a concentration in the soil of 30 mg/kg or more but several Pb tolerant plants have been reported. However, few studies have focused on plant response to Pb exposure, particularly at concentrations higher than 30 mg/kg. The assessment and evaluation of metal dose-dependent plant responses will assist in future phytoremediation studies. Therefore, this work documents the Pb concentration-dependent antioxidative response in Tetraena qataranse. Young seedlings were irrigated with 0, 25, 50, and 100 mg/L Pb every 48 h for seven weeks under greenhouse conditions. A phytotoxicity test showed that at the lowest treatment concentration, Pb stimulates growth. However, at 100 mg/L (1600 mg/kg Pb in the growth medium at harvest), the metal disrupted healthy growth in T. qataranse, particularly root development. Metal accumulation in the root was higher (up to 2784 mg/kg) than that of the shoot (1141.6 mg/kg). Activity assays of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione reductase (GR) showed a progressive increase in enzymatic activities due to Pb treatment. Together, the results of this study suggest that T. qataranse is a Pb hyperaccumulator. Increased antioxidant enzyme activity was essential to maintaining cellular homeostasis and assisted in the arid plant's tolerance to Pb stress.

The interplay between light, plant growth regulators and elicitors on growth and secondary metabolism in cell cultures of Fagonia indica.

Manipulation in the light regimes combined with the effects of plant growth regulators (PGRs) and elicitors through plant cell culture technology is a promising strategy for enhancing the yield of medicinally important secondary metabolites. In this study, the effects of interplay between PGRs, elicitors and light regimes on cell cultures of F. indica have been investigated. The results showed that callus cultures resulted in maximum biomass formation (13.2 g/L) when incubated on solid MS (Murashige and Skoog) medium containing 1.0 mg/L BA under continuous light for 4 weeks. Among the other PGRs, compared with the auxins such as 2,4-D, and IBA, TDZ resulted in higher biomass accumulation (12.1 g/L). Elicitors (Me-J and PAA) resulted in a lower growth response, when compared with cytokinins and a higher response than auxins under all the light regimes on solid MS media. However, in liquid media, no significant increase in biomass was observed in response to the combined effects of PGRs and photoperiod regimes. Further, the highest phenolic content (TPC = 6.8 mg) and flavonoid content (TFC = 5.2 mg) were detected in the dark-grown cell cultures raised in vitro at 0.5 mg/L Me-J. The highest antioxidant activity (88%) was recorded in the dark-grown cell cultures harvested from LOG phase of the growth cycle supplemented with 0.5 mg/L Me-J. Furthermore, BA resulted in considerable flavonoids production (TFC = 4.7 mg) in the cell cultures grown under continuous light. However, overall dark treatment and elicitation with Me-J resulted in the optimal metabolic response in terms of secondary metabolites accumulation in cell suspension cultures of F. indica.

Comparative exine ontogeny in some members of the family Zygophyllaceae sensu lato.

Exine ontogeny is studied in five taxa of the family Zygophyllaceae sensu lato (Peganum harmala L., Zygophyllum album L., Fagonia cretica L., Tribulus terrestris L., and Nitraria retusa [Forsk.] Asch.). In the beginning of the tetrad stage, the plasmalemma is attached to the callose wall, except in T. terrestris, where it describes crests and hollows. The primexine matrix is fibrillar, bilayered in T. terrestris and unilayered in the other taxa. In all species except P. harmala, the procolumellae are heterogeneous with clear zones and they become compact later. In T. terrestris, they are built on the crests. In Z. album and T. terrestris, a primordial nexinic lamella is set up. It is tripartite with a white line seen at some levels; on its external leaflet, the foot layer is observed, and on its internal leaflet, there is the endexine with numerous lamellae. This white line disappears often in the mature exine. In T. terrestris, there is a thick nexine that is coarsely lamellate inside. In the aperture zone, the columellae are lacking, the tectum and the foot layer get thinner; they unite and form the apertural membrane with the external part of the endexine. There is a granulolamellar endexinic zone well developed in P. harmala, whereas it is threelayered and weakly developed in T. terrestris.