No abstract

Ultraviolet B radiation has been described as a potential elicitor agent of the synthesis of secondary metabolites in plants. Thus, the present study aimed to investigate the production of betalains and total flavonoids, as well as the antioxidant activity, of Alternanthera sessilis, A. brasiliana, A. tenella and A. philoxeroides exposed to different periods of UV-B radiation (280-315 nm). Plants of these four species were exposed to UV-B radiation for 0, 2, 4, 6, and 8 hours, which amounts to 0, 10, 20, 30, and 40 J cm −2 of radiation, respectively. Significant increases in betacyanin and betaxanthin levels were observed in A. sessilis and A. brasiliana during the period of UV-B exposure, while no differences were observed for the others species. The highest estimated flavonoid levels were for A. sessilis exposed to UV-B radiation for 8 h, followed by a 24 h recovery period. In conclusion, the action of UV-B radiation as an inducer of defence responses in plants is influenced by increasing exposure periods followed by a recovery period. Both increase the levels of these composts, yet this increase is different among the four Alternanthera species, having a greater influence on the species A. sessilis and A. brasiliana.

This research investigates effects of salicylic acid (an abiotic elicitor) on the antioxidant activity and betacyan production from leaves of

-(Potential allelopathic and antibacterial activity of Alternanthera philoxeroides). Alternanthera philoxeroides is a promising species in the search for new molecules with biological effects. To accelerate this bioprospection process of A. philoxeroides, the chosen methods (allelopathy and discdiffusion technique) are excellent alternatives. The purpose of this study was to evaluate the allelopathic effects and verify the antibacterial properties of extracts from A. philoxeroides. To evaluate the antibacterial activity, disc diffusion technique was used with five reference strains. The germination test was conducted with the extracts at concentrations of 0, 1.0, 2.0 e 3.0 mg mL -1 in a petri dish with 30 lettuce seeds and for the growth trial 10 seeds were used. The experimental design was completely randomized in factorial 4 × 2 × 4 (four extracts, two sources, four concentrations), with four replicates.The results indicate that the lettuce germination was influenced by ethyl acetate fraction obtained from leaves of A. philoxeroides at the highest concentrations; however, the germination speed and the radicle growth were significantly affected by all the extracts starting at 1mg mL-1 concentration. Those results demonstrate allopathic effect of different extracts of this plant, although they have not interfered with the strains growth used in this experiment.

is an important source of natural steviol glycosides and is of increasing interest in various fields of study. Therefore, understanding the molecular processes regulating its metabolism is of great importance. In this study, the stability of seven reference genes (- and ) under the effect of three stress-related elicitors (methyl jasmonate, salicylic acid, and spermidine) was evaluated in stevia plants. We used RefFinder software, which makes use of the four main currently available algorithms for reference gene selection: geNorm, NormFinder, BestKeeper, and the Comparative ∆Ct method. The results indicated that and can be used as reference genes under all tested experimental conditions. The genes, traditionally used as a reference gene, along with , showed the lowest stability. The expression of-- and genes was used to confirm the validated reference genes, showing that inadequacy of the reference gene may lead to erroneous results. This is the first study on the stability of reference genes in plants, and is of great relevance for further analysis of the gene expression of the steviol glycoside biosynthetic pathway.

The aim of the present study was to investigate the influence of tyrosine on the in vitro growth and the production of the betacyanin pigment in Alternanthera philoxeroides and A. tenella. Nodal segments were inoculated in MS medium containing different concentrations of tyrosine (0, 25, 50 and 75 µM)

No abstract

A manipulação da concentração dos microelementos no meio de cultura representa uma boa estratégia para aumentar a produção de metabólitos secundários em cultura de tecidos. Este trabalho teve por objetivo demonstrar a influência do sulfato de cobre na produção de betacianina e na multiplicação de plantas de Alternanthera philoxeroides (erva-de-jacaré) (0; 25; 75; 125; 175; 200µM) (0, 25, 75, 125, 175, 200µM