This research was carried out to study the effect of TiO2 and nano-TiO2 on some chemical compounds in a medicinal plant Lallemantia iberica under water deficit conditions. The experiment was conducted as a factorial arrangement in a randomized complete block design with three replications. The first factor was the application of external materials as spraying with 3 levels of control, TiO2 and nano-TiO2, and the second factor was 100% (no stress), 75% (moderate stress) and 35% (severe stress) irrigation content. The results of measurements showed moderate stress and the use of nano-TiO2 caused a significant increase in phenolic content, total flavonoid and antioxidant activity; severe drought stress significantly reducing these compounds. The effect of nano-TiO2 on catalase and superoxide dismutase enzyme activity was also significant, and in the treatment of nano-TiO2 and moderate stress, the highest activity level of these two enzymes was observed. Identification of phenolic compounds of the extracts by HPLC indicated the production of vanillic, ferulic acid and syringic acid by nano-TiO2 spray application. Gallic acid was measurable in moderate and severe stress and caffeic acid in severe stress under the influence of nTiO2. The sinapic acid and syringic acid contents increased under moderate stress and severe stress decreased them. Finally, it is concluded that nano-TiO2 in comparison with TiO2 reduces the effects of drought stress on L. iberica and can be used to produce this plant in water-deficit areas. Manuscript profile

Peppermint infusion is a popular herbal drink with a number of benefits on cardiovascular, digestive, respiratory systems. Recent researches demonstrated that ultraviolet radiation can have an effect on peppermint essential oil. Considering the actual increasing of UV-B in the sun radiation, it’s important to estimate real conditions and which economic consequences it may have. Mentha x piperita L. plants grown in field were irradiated for one hour with UV-B light (310 nm, 3.8 Wm-2), in the middle of the day, for two days. The five upper leaves were collected at 4, 20, 24, 28, 44 and 48 h after the first treatment. Plants of M. x piperita cultivated under the same circumstances without the treatment were utilized as the control at each time point. Results showed that the biosynthesis of peppermint essential oil is modulated by UV-B irradiation, but the plants have also their mechanisms of protection from UV by increasing the ROS-scavenging enzymes activity. Also, expression of some involved genes in pathway modified in the presence of UV and showed regulating effect in essential oil biosynthesis significantly. Another confirmation of the protection from UV-B light was the stable concentration of photosynthetic pigments. Analysis of ROS-scavenging enzymes suggests that plants had an oxidative stress. In conclusion, this work is a one step to understand the regulation of terpenoid biosynthesis and the effects of UV-B radiation on it. Complex analysis of whole plant’ response will be helpful for this aim. Manuscript profile