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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.

-(Callus induction and betacyanin quantification by HPLC/MS-MS in Alternanthera brasiliana (L.) Kuntze).The objective of this study was to establish a protocol for callus induction and betacyanin production in plants of Alternanthera brasiliana. Explants of A. brasiliana and five combinations of cytokinin and auxin were used for callus induction. Calli were transferred to a Betacyanin Induction Medium (MIB), composed of MS, with 0.5 mg L -1 of thidiazuron (TDZ) and 1 mg L -1 of naphthaleneacetic acid (NAA), and kept in the light for 45 days. The aspect and intensity of pigments were assessed and total betacyanins were quantified in high performance liquid chromatography (HPLC). The combination of internodal segments and a medium containing equilibrium concentrations of auxins and cytokinins was the most efficient metod to induce calli and increased production of betacyanins. The presence of amaranthine in calli of A. brasiliana justifies its medical use and the consequent need for future studies for the large-scale production of this molecule. Keywords: in vitro growth, medicinal plants, phyto-regulators, pigments RESUMO -(Indução de calo e quantificação de betacianinas por CLAE/MS-MS em Alternanthera brasiliana (L.) Kuntze). O objetivo deste estudo foi estabelecer um protocolo para indução de calos e produção de betacianinas em plantas de Alternanthera brasiliana. Para indução da calogênese foram utilizados explantes de A. brasiliana e cinco combinações de citocinina e auxina. Posteriormente os calos foram transferidos para Meio de Indução de Betacianinas (MIB), formado por meio MS, com 0,5 mg L -1 de tidiazuron (TDZ) e 1 mg L -1 de ácido naftalenoacético (ANA), onde permaneceram na luz por 45 dias. Avaliou-se oaspecto e a intensidade de pigmentos e quantificação de betacianinas totais em Cromatografia Líquida de Alta Eficiência (CLAE). Os segmentos internodais combinados com o meio que contém equilíbrio na concentração de auxinas e citocininas foi mais eficiente para obtenção de calogênese e maior produção de betacianinas. A presença de amarantina, em calos de A. brasiliana, justifica seu uso medicinal e contribui para futuros estudos para produção em larga escala desta molécula. Palavras-chave: cultivo in vitro, fitorreguladores, plantas medicinais, pigmentos

Alternanthera brasiliana is a medicinal plant with several popular use and high production of betalains. The aim of the present research was to establish a protocol for callus induction and betalain biosynthesis in A. brasiliana species, as well as to investigate the effect of different qualities of light in increasing betalain in A. brasiliana callus cultures. In this way, the callus initiation and the improvement of secondary metabolites were induced using varying phytohormones concentrations and under the influence of red, white and blue lights. To start the experiments, the plants were cultivated for 30 days in Murashige and Skoog (MS) medium to grow and form internodes. These were inoculated in MS medium supplemented with different combinations of plant growth regulators to find the best combination for medium callus induction (MCI). After another 30 days, the explants were transferred to a medium for betacyanin induction (MBI) containing thidiazuron (TDZ) and α-naphthalene acetic acid (NAA) under blue, white, and red lights. The best medium for A. brasiliana callus induction with higher production of betalains, was the MS medium supplemented white indole-3-acetic acid (IAA) and 2,4dichlorophenoxyacetic acid (2,4-D), before inoculation on the MBI. The blue and white lights promoted callus pigmentation (betalains), whereas the red light was not effective at inducing pigmentation in the calli.