Effect of Ulex europaeus L. extracts on polyphenol concentration in Capsicum annuum L. and Lactuca sativa L.

In this work, the effect of aqueous and methanolic extracts from roots and shoots of Ulex europaeus L. on the total polyphenol content of Capsicum annuum L. and Lactuca sativa L. grown in laboratory and greenhouse conditions was evaluated. Treatments consisted of U. europaeus L. extracts (20, 40, 80, 160 and 320 mg kg-1) as well as caffeine and distilled water as controls, all of which were applied with a manual sprayer on seedlings of the aforementioned species. Total polyphenols were determined using the Folin-Ciocalteu method. Under control conditions, the polyphenol concentration in C. annuum was lower in laboratory than in greenhouse conditions (P<0.05). Conversely, L. sativa had a higher polyphenol concentration in the laboratory than in the greenhouse (P<0.05). Also, under laboratory conditions the polyphenol content rose with increasing extract doses in both species, but this tendency was not observed in the greenhouse. Finally, different doses of extracts of U. europaeus L. affect total polyphenol content in both species. This effect is clear under laboratory conditions, but not in greenhouse experiments. These findings open up the possibility of cultivating species with higher antioxidant contents using natural products

Metallic nanoparticles influence the structure and function of the photosynthetic apparatus in plants

The applications of nanoparticles continue to expand into areas as diverse as medicine, bioremediation, cosmetics, pharmacology and various industries, including agri-food production. The widespread use of nano particles has generated concerns given the impact these nanoparticles mostly metal-based such as CuO, Ag, Au, CeO2, TiO2, ZnO, Co, and Pt - could be having on plants. Some of the most studied variables are plant growth, development, production of biomass, and ultimately oxidative stress and photosynthesis. A systematic appraisal of information about the impact of nanoparticles on these processes is needed to enhance our understanding of the effects of metallic nanoparticles and oxides on the structure and function on the plant photosynthetic apparatus. Most nanoparticles studied, especially CuO and Ag, had a detrimental impact on the structure and function of the photosynthetic apparatus. Nanoparticles led to a decrease in concentration of photosynthetic pigments, especially chlorophyll, and disruption of grana and other malformations in chloroplasts. Regarding the functions of the photosynthetic apparatus, nanoparticles were associated with a decrease in the photosynthetic efficiency of photosystem H and decreased net photosynthesis. However, CeO2 and TiO2 nanoparticles may have a positive effect on photosynthetic efficiency, mainly due to an increase in electron flow between the photo systems II and I in the Hill reaction, as well as an increase in Rubisco activity in the Calvin and Benson cycle. Nevertheless, the underlying mechanisms are poorly understood. The future mechanistic work needs to be aimed at characterizing the enhancing effect of nanoparticles on the active generation of ATP and NADPH, carbon fixation and its incorporation into primary molecules such as photo-assimilate