Nanoparticles (NPs) have emerged as one of the most innovative and promising application in agriculture. Since plants are recognized as essential component of all ecosystems, the effects of NPs on plants may pave a new insight to the ecosystems. Here, uptake and translocation of superparamagnetic iron oxide NPs (SPIONs), with various surface charges, on soybean has been probed; in addition, the effects of SPIONs on variations of chlorophyll, in hydroponic condition, together with their ability for reduction of iron deficiency chlorosis were explored. We find that SPIONs, which were entered and translocated in the soybean, increased chlorophyll levels, with no trace of toxicity. Furthermore, it was found that physicochemical characteristics of the SPIONs had a crucial role on the enhancement of chlorophyll content in subapical leaves of soybean. The equivalent ratio of chlorophyll a to b, in all treatments with conventional growth medium iron chelate and SPIONs (as iron source), indicated no significant difference on the photosynthesis efficiency. Finally, it was observed that the effect of SPIONs on the soybean chlorophyll content may have influence on both biochemical and enzymatic efficiency in different stages of the photosynthesis reactions.

considering titanium dioxide nanoparticles (tio 2 nps) role in plant growth and especially in plant tolerance against abiotic stress, a greenhouse experiment was carried out to evaluate TiO 2 NPs effects (0, 50, 100 and 200 mg L −1) on agronomic traits of Moldavian balm (Dracocephalum moldavica L.) plants grown under different salinity levels (0, 50 and 100 mM NaCl). Results demonstrated that all agronomic traits were negatively affected under all salinity levels but application of 100 mg L −1 tio 2 nps mitigated these negative effects. TiO 2 NPs application on Moldavian balm grown under salt stress conditions improved all agronomic traits and increased antioxidant enzyme activity compared with plants grown under salinity without tio 2 NP treatment. The application of TiO 2 NPs significantly lowered H 2 o 2 concentration. In addition, highest essential oil content (1.19%) was obtained in 100 mg L −1 tio 2 nptreated plants under control conditions. Comprehensive GC/MS analysis of essential oils showed that geranial, z-citral, geranyl acetate and geraniol were the dominant essential oil components. The highest amounts for geranial, geraniol and z-citral were obtained in 100 mg L −1 tio 2 np-treated plants under control conditions. In conclusion, application of 100 mg L −1 tio 2 NPs could significantly ameliorate the salinity effects in Moldavian balm. Moldavian balm (Dracocephalum moldavica L.), a perennial herb of the Lamiaceae family and native to central Asia, naturalized in central and eastern Europe and is cultivated around the world as a medicinal plant. Essential oils and extracts of Moldavian balm have been traditionally used as a painkiller for kidney complaints, toothache and colds. In addition, it has antimicrobial activities 1 , antirheumatic, antitumor, antimutagenic, antioxidant and antiseptic properties 2. Aerial parts of Moldavian balm are important sources of monoterpene glycosides, trypanocidal terpenoids, rosmarinic acid and flavonoids 3. Salinity stress is considered as one of the main environmental factors limiting plant distribution in their natural habitats 4. Soil salinity affects about 800 million hectares of arable land worldwide. Salinity stress causes major problems regarding plant growth, development and productivity, especially in arid and semi-arid regions of the world 5 manifested as changes in morphological, physiological and biochemical characteristics of plants, ion toxicity (Na + and Cl −), nutritional disorders and osmotic stress. These negative impacts significantly decrease plant

To date enormous attempts have been devoted to improve Taxol production exploiting various methodologies from bioprocess engineering to biotechnological and synthetic approaches. We have developed a 2-stage suspension cell culture of Taxus baccata L. using modified B5 medium in order to improve cell growth as well as productivity. After callus induction and cell line selection, B5 medium was supplemented with vanadyl sulfate (0.1 mg/l), silver nitrate (0.3 mg/l) and cobalt chloride (0.25 mg/l) at the first day of stage I culture to maximize cell growth. This medium was further supplemented with sucrose (1%) and ammonium citrate (50 mg/l) on day 10 and sucrose (1%) and phenylalanine (0.1 mM) on day 20 (i.e., biomass growth medium). At stage II (day 25), two different concentrations of several elicitors such as methyl jasmonate (10 or 20 mg/l), salicylic acid (50 or 100 mg/l) and fungal elicitor (25 or 50 mg/l) were added to the biomass growth medium with the aim of improving cellular productivity. For morphological analysis, microscopic inspection was carried out during cultivation. Cell-associated and extracellular amount of Taxol were detected and measured using HPLC methodology. At stage I, overall Taxol amount of biomass growth medium was 13.75 mg/l (i.e., 5.6-fold higher than that of untreated B5 control). At stage II, treated cells with methyl jasmonate (10 mg/l), salicylic acid (100 mg/l) and fungal elicitor (25 mg/l) produced the highest amount of Taxol (39.5 mg/l), which is 16-fold higher than that of untreated B5 control (2.45 mg/l). Microscopic analyses of Taxus cells in suspension cultures showed various positional auto-fluorescence showing direct correlation with Taxol production. Our studies revealed that intervallic supplementation of B5 medium with combination of biomass growth factors at stage I and mixture of elicitors at stage II could significantly increase Taxol production. Thus, we suggest that the exploitation of this methodology may improve the production of Taxol since demands for Taxol pharmaceuticals are increasingly growing and resource paucities have limited its direct harvesting from Taxus trees.

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