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Previous issue date: 2011-10-31 / The medicinal Alternanthera (Amaranthaceae) species, such as A. philoxeroides, present a great
variety of bioactive compounds, among which are the betacyanins, nitrogen pigments that belong
to the betalains class. These compounds are widely used as additives for food and drugs, due to
their antioxidant action and lack of toxicity, which have already been proven. Techniques have
been developed in order to improve productivity and performance of this pigment, one of those is
the use of in vitro elicitors or in vivo stressing agents. Both have an important role in the
transduction process of signals that regulate the defense genes in plants, acting as stimulators of
production or degradation of several primary and secondary metabolites. This work aimed to
assess, in A. philoxeroides plants, the growth and production characteristics of betacyanin in in
vitro plants; the levels of photosynthetic pigments, betacyanins, lipid peroxidation and antioxidant
enzymes activity in in vivo plants under salt stress, and also to quantify the level of betacyanin and
the 5GT-DBs gene expression in the biosynthetic route of this compound in in vitro plants
submitted to elicitation by NaCl and by tyrosine. For this, three trials were conducted. In the first
one, A. philoxeroides explants were inoculated in MS medium with increasing NaCl concentrations
(0, 50, 100, 150, 200 and 250 mM) for 35 days. In the second one, plants from in vitro cultures
were acclimatized in greenhouses and irrigated with a sodium chloride solution (0, 200 and 400
mM) for 30 days. The third trial had two essays, one composed of in vitro A. philoxeroides plants in
a liquid MS medium in vermiculite substrate for 35 days. After this period, a NaCl solution (400
mM) was added to the medium and the shoots were collected after 0, 12, 24, 36 and 48 hours of
exposure. In the second one, nodal segments were inoculated in MS medium with and without
tyrosine (0 e 75 µM), and its aerial parts were collected after 35 days. In the growth analysis,
reduction of the averages was observed for the following variables: height, number of shoots,
number of sprouts and root number and length; for the plants that have grown in the sodium
chloride medium. The highest concentrations of betacyanins were found in the stalks of plants from
MS medium, with 50 mM of NaCl. After 30 days of in vivo cultivation, the levels of chlorophyll a,
chlorophyll b and carotenoids decreased as the salt concentration increased, while the reason of
chlorophyll a/b in plants submitted to a higher salt concentration presented a difference in
comparison to the control. Higher levels of betacyanin were observed on stalks, when compared to
the leaves, in the highest salt concentrations. On the leaves, there was a significant increase of
lipid peroxidation and superoxide dismutase activity. On the roots, there was an increase of
enzymes catalase and ascorbate peroxidase. Regarding the analysis of differential expression
(qRT-PCR), it was possible to observe that from 12 to 24 hours of salt stress, the 5-GT gene
expression firstly increased, then there was a decrease in 36 hours and a new increase in 48
hours. The 5-GT gene also showed increased expression as a response to tyrosine. It was
possible to conclude that A. philoxeroides elicited in vitro with sodium chloride present a decrease
of the assessed morphological parameters, but in low concentrations betacyanin synthesis is
stimulated. Salt stress causes greater degradation in the photosynthetic pigments, increment of
betacyanin synthesis in stalks and damage to the cell membranes of the leaves. The increase of antioxidant enzymes activity stimulated the protective system against oxidative stress on in vivo A.
philoxeroides plants. It is suggested that in this species, the enzyme bethanidine 5-Oglucosyltransferase
reaches its highest expression in 48 hours of exposure to salt elicitation and
also when grown in a medium containing tyrosine. / As espécies medicinais do gênero Alternanthera (Amaranthaceae) como A. philoxeroides
apresentam uma variedade de compostos bioativos, entre eles as betacianinas, que são
pigmentos nitrogenados pertencentes à classe das betalaínas. Esses compostos são
amplamente utilizados como aditivos de produtos alimentícios e medicamentos devido à
sua comprovada ação antioxidante e ausência de toxicidade. Técnicas têm sido
desenvolvidas para aprimorar a produtividade e o rendimento deste pigmento, sendo uma
delas o uso de elicitores in vitro ou agentes estressantes in vivo. Ambos apresentam um
importante papel no processo de transdução de sinais que regulam os genes de defesa
nas plantas, agindo como estimuladores para a produção e ou degradação de diversos
metabólitos, tanto primários quanto secundários. Assim, o objetivo do presente trabalho
foi avaliar em plantas de A. philoxeroides, as características de crescimento e produção
de betacianina em plantas cultivadas in vitro; os teores dos pigmentos fotossintéticos,
betacianinas, peroxidação lipídica e atividade de enzimas antioxidantes em plantas
cultivadas in vivo, sob estresse salino, além de, quantificar o teor de betacianina e a
expressão do gene 5GT-DBs envolvido na rota biossintética, deste composto, em plantas
in vitro submetidas à elicitação por NaCl e pelo aminoácido tirosina. Para isso, foram
conduzidos três experimentos. No primeiro, explantes de A. philoxeroides foram
inoculados em meio MS, com concentrações crescentes de NaCl (0, 50, 100, 150, 200 e
250 mM), durante 35 dias. No segundo, plantas provenientes da cultura in vitro foram
aclimatizadas em casa de vegetação e irrigadas com solução de cloreto de sódio (0, 200
e 400 mM), por 30 dias. O terceiro experimento contou com dois ensaios, sendo o
primeiro composto de plantas de A. philoxeroides cultivadas in vitro, em meio MS líquido,
no substrato vermiculita, durante 35 dias. Após esse período, foi adicionada ao meio,
solução de NaCl (400 mM) e coletada a parte aérea das plantas após 0, 12, 24, 36 e 48
horas de exposição ao sal, Já o segundo, segmentos nodais foram inoculados em meio
MS, na presença e ausência de tirosina (0 e 75 µM), tendo sua parte aérea coletada após
35 dias de cultivo. Nas análises de crescimento observou-se redução das médias para as
variáveis altura, número de gemas, número de brotos e no número e comprimento de raiz,
nas plantas crescidas nos meios contendo cloreto de sódio. As maiores concentrações de
betacianinas foram encontradas nos caules de plantas cultivadas em meio MS com 50
mM de NaCl. Após 30 dias de cultivo in vivo os teores de clorofilas a, clorofila b, e
carotenóides decresceram à medida que aumentou a concentração de sal, enquanto a
razão clorofila a/b das plantas submetidas à maior concentração de sal apresentou
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufpel.edu.br:123456789/2051 |
| Date | 31 October 2011 |
| Creators | Ribeiro, Márcia Vaz |
| Contributors | CPF:44117337068, http://lattes.cnpq.br/7705049074927773, Peters, José Antonio, Braga, Eugenia Jacira Bolacel |
| Publisher | Universidade Federal de Pelotas, Programa de Pós-Graduação em Fisiologia Vegetal, UFPel, BR, Biologia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFPEL, instname:Universidade Federal de Pelotas, instacron:UFPEL |
| Rights | info:eu-repo/semantics/openAccess |
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