Relatório de actividades
Guedes, Cristina Vitória de Miranda
1992
Search results
33 records were found.
The Pterospartum tridentatum (L.) Willk is widely used as medicinal plant
for the treatment of digestive tract diseases and diabetes and for culinary
purposes, however, characterization studies on this plant extracts are scarce.
This work aimed to develop methodologies for micropropagation of
this species and carry out characterization and application of the aqueous
extracts. This study represents the first comparison analysis of extracts obtained
from wild plants and aerial parts of plants in vitro multiplication. Micropropagation was very effective on large scale propagation with
high multiplication rates.
Aqueous extracts showed a good performance, high levels of phenolic
compounds and antioxidant activity both in wild plants and in micropropagation.
Phenolic profiles in in vitro shoots are very similar to extracts of
wild plants during vegetative rest.
The extracts revealed no antifungal activity, but nevertheless evidenced
inhibition for some microorganisms.
Within the monosaccharides, glucose is the predominant sugar in wild
plants, since in the in vitro shoots uronic acids are the main components.
An interesting result was the higher molar percentages of rhamnose and
uronic acids detected on in vitro shoots compared to wild plants, which
can make the in vitro plant material very useful to obtain these compounds.
The application of chitosan bioactive coatings incorporating extracts
has improved post-harvest storage capacity in cherry. The results allow propose
these methodologies for obtaining extracts with bioactive properties
from micropropagated material without depleting natural resources.
Comunicação apresentada no Simpósio de Propagação Vegetativa de Espécies Lenhosas que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 18 a 20 de Outubro de 1996.
Referem-se alguns dos aspectos históricos que mais contribuíram para o desenvolvimento do conhecimento na área da cultura de tecidos vegetais, bem como a grande diversidade de aplicações e utilização destas metodologias, desde os estudos fisiológicos, interacções substâncias/planta, produção de metabolitos secundários, manipulação genética e melhoramento até à sua utilização como uma poderosa metodologia na multiplicação de plantas, quer por rebentamento adventício, axilar quer por embriogénese somática. Faz-se uma descrição sucinta dos aspectos que maior impacto têm vindo a ter com a utilização destas metodologias nos diferentes grupos de culturas vegetais, nomeadamente nas culturas extensivas, hortícolas, ornamentais, fruteiras e florestais.
Referem-se alguns dos aspectos históricos que mais contribuíram para o desenvolvimento do conhecimento na área da cultura de tecidos vegetais, bem como a grande diversidade de aplicações e utilização destas metodologias, desde os estudos fisiológicos, interacções substâncias/planta, produção de metabolitos secundários, manipulação genética e melhoramento até à sua utilização como uma poderosa metodologia na multiplicação de plantas, quer por rebentamento adventício, axilar e embriogénese somática.
Faz-se uma descrição sucinta dos aspectos que maior impacto têm vindo a ter com a utilização destas metodologias nos diferentes grupos de culturas vegetais, nomeadamente nas culturas extensivas, hortícolas, ornamentais, fruteiras e florestais.
Great advances have been made but some cultured plantlets still having a poor performance during the ex vitro stages and more specifically during the acclimatization and the nursery establishment stages. The problem is highly complex and requires the fast adaptation of plants growing in artificial conditions when transferred to the natural conditions. Until now, there is no consensus on the better strategy to obtain a higher efficiency of the propagation protocols while optimising acclimatization success. In this study we present the results of growth analysis of in vitro-regenerated chestnut hybrid plantlets (Castanea sativa x C. crenata), during the acclimatization stage, using two CO2 concentrations (350 µLL-1 and 700 µLL-1) at 250 µmol m- 2 s-1 as irradiance level (PPFD). Elevated CO2 did not affect the survival rate and it was susceptible to increase progressive autotrophy, expressed by a significant increase in relative growth, shoot/root ratio and leaf area ratio (LAR). For both CO2 concentrations, the plants are successfully acclimatized and they are in good conditions to be transferred to a greenhouse to continue their development for the rest of the season, and in the next winter/spring they can go to the field. The plants under elevated CO2 showed a higher stomatal frequency but the new leaves developed at the end of acclimatization revealed a gradual normal stomatal morphology and they reduced the stomatal frequency. Their morphology showed an effective water loss control, which is one of the most important problems during this critical phase of the autotrophic competence acquiring process. The net photosynthesis rate (A) was similar in both treatments but the plants acclimatized at elevated CO2 showed an increase in maximum photosynthetic rate (Amax), and this can lead to a better physiological development. The different analysed leaf types showed a marked increment of the maximum photosynthetic rate as the new leaves developed during the acclimatization stage. Net photosynthesis rate and the maximum photosynthetic rate are light dependent, and are positively affected by the highest irradiance level. We think that the gains that we have achieved with the use of elevated CO2 can be more significant if a higher light intensity can be used instead because they have a better response capacity to an increment of the level of irradiance.
A realização desta Jornada Técnica sobre o Castanheiro, inseriu-se no âmbito da divulgação do Potojecto PAMAF 6127.
Comunicação oral apresentada no II International Symposium on Acclimatization and Establishment of Micropropagated Plants que decorreu em 2004 em Cancún, no México.
The aim of this study was to compare two rooting environmental conditions for root development, in vitro and ex vitro, and their influence in anatomical differentiation.
Comunicação oral da qual só está disponível o resumo.
O objetivo deste trabalho foi realizar um estudo comparativo em microplantas de castanheiro com dois sistemas de expressão e desenvolvimento radicular, in vitro e ex vitro, e com duas intensidades luminosas (150 e 250 μmol m-2 s-1) durante a aclimatização, e a sua influência no desenvolvimento das microplantas durante esta fase, através da quantificação de parâmetros fotossintéticos. A concentração de clorofilas, após os tratamentos de aclimatização, dependeu quer do tipo de sistema radicular que as plantas possuíam no início da aclimatização, quer do regime luminoso a que as plantas estiveram submetidas.
As plantas com enraizamento in vitro e aclimatizadas sob menor irradiância foram as que apresentaram valores superiores para a clorofila total (7,74 mg g-1ps), mas com o valor mais baixo na razão entre clorofila a/b (2,7).
Quando comparamos os valores registados para os parâmetros fotossintéticos das plantas dos diferentes tratamentos, verificamos que as taxas de fotossíntese aparente vão gradualmente aumentando à medida que as novas folhas se vão desenvolvendo (0,75 μmol CO2 m-2 s-1 nas folhas persistentes e 3,43 μmol CO2 m-2 s-1 na folha 3 das plantas aclimatizadas a 250 μmol m-2 s-1). O mesmo acontece na capacidade fotossintética (3,93 μmol O2 m-2 s-1 nas folhas persistentes e 7,87 μmol O2 m-2 s-1 na folha 3 das plantas aclimatizadas a 250 μmol m-2 s-1). Estes valores foram tendencialmente superiores nas plantas com enraizamento ex vitro e aclimatizadas a maior irradiância, pelo que a um melhor sistema radicular e uma maior disponibilidade luminosa correspondeu um acréscimo na competência fotossintética, o que resultou num melhor desenvolvimento morfofisiológico das plantas.
Endogenous levels of IAA, IAAsp and IBA were quantified during the first 8 days of in vitro rooting of the chestnut hybrid, clone M3 by high performance liquid chromatography. Rooting was induced either by dipping the basal ends of the shoots into 1 gl-1 IBA solution for 1 minute or by subculturing the shoots on agar rooting medium with 3 mgl-1 IBA for 5 days. For root development the induced shoots were transferred to auxin-free agar medium. Auxins were measured in the apical and basal parts of the shoots by means of high performance liquid chromatography. Endogenous levels of IAA and IAAsp were higher in IBA-treated shoots than in control shoots. In extracts of the basal parts of the shoots, the concentration of free IAA showed a transient peak at day 2, in both root inductive methods, a subsequent gradual decrease for the remainder of the time course was observed. The concentration of IAAsp peaked at day 6 in extracts of the basal parts of shoots induced with 3 mgl-1 IBA for 5 days, whereas shoots induced by dipping showed an initial increase until day 2, and then remained stable. In extracts from basal shoot portions induced by dipping and by IBA in the medium, IBA concentration showed a transient peak at 24 h and 48 h, respectively, remaining stable after day 4 for the dipping method, whilst showing a significant drop between day 4 and 6 for the other induction treatment. All quantified auxins remained at a relatively low level, virtually constant, in extracts from apical shoot portions, as well as in extracts from control of non-rooting shoots.
In this study we aimed at studying the in vitro propagation of common myrtle.
The aim of the present study was to evaluate the total phenolic content and antioxidant activity of aqueous extracts of Pterospartum tridentatum samples, collected in three locations in Portugal, at diferente vegetative stages.
The use of medicinal plants for the extraction of active pharmacological agents and precursors for chemical-pharmaceutical chemosynthesis has recently increased. The aim of this work was to study the establishment and multiplication phases of the in vitro propagation of common myrtle (Myrtus communis L.). In the establishment phase, the most suitable disinfection method was found by using increasing concentrations of commercial bleach (10%, 15% and 20%). It was discovered that commercial bleach at 15% allowed better results in the shoots survival rate (87%). The concentrations used to establish the explants from adult plant material did not allow however that all of them survived. This was possibly due to the some release of phenolic substances, and, also, to a certain toxicity of the disinfectant used, especially at the highest concentration. During the multiplication phase it was intended to assess the influence of light, through coloured bottle caps, on the shoots growth rate parameters, but we observed that it had no influence on the average of the longest shoot, on the average of the smaller shoot, and also, on the parameters related to the multiplication rate, the number of shoots and the number of shoot segments.
The aerial parts of Pterospartum tridentatum, a wild growing species in Portugal used in
traditional medicine and gastronomy, were harvested at different stages (vegetative phase, flowering
phase and beginning of dormancy) in two locations in Portugal (Malcata and Gardunha mountains),
and the respective aqueous extracts have been studied. The influence of the seasonal variation in the
extraction yield, total phenolic content and antioxidant activity was evaluated. The extraction was
carried out in boiling water in consecutive steps. After each step, the aqueous extract was separated
and fresh water was added maintaining the same plant material. The procedure was repeated seven
times, within an overall time period of 180 minutes.
Higher extraction yields were achieved with plant stems collected at the vegetative phases, either from
Malcata or Gardunha regions. The total phenolic content of the extracts from Malcata plants ranged
from 273 mg to 400 mg gallic acid equivalent/g dry matter, which was quite similar to that determined
for extracts from Gardunha (245 to 394 mg gallic acid equivalent/g dry matter). The antioxidant activity
was determined by the radical scavenging activity method using 2,2-diphenyl-1-picrylhydrazyl radical
(DPPH). The greatest radical scavenging activity was observed in the flowers extracts, even though all
extracts produced presented a good antioxidant activity. Furthermore, the antioxidant activity was not
affected by the exposure of the plant material at 100ºC for long periods of time (180 min).
The results show that Pterospartum tridentatum has a great potential to be used as a new source of
natural antioxidants for the food industry.
Tendo em vista a valorização deste recurso natural, este trabalho tem como principal objectivo a produção de extractos aquosos das partes aéreas da carqueja e a sua caracterização.
Comunicação da qual só está disponível o resumo.
Identificação de compostos bioativos em plantas silvestres e plantas in vitro de Pterospartum tridentatum (L.) Willk.
Atividade antioxidante e antimicrobiana de extratos de plantas de Pterospartum tridentatum (L.) Willk. in vitro e silvestres.
Fruit juice does not have the same nutritional value as fresh fruit with regards to the vitamin, mineral and dietary fibre contents and the antioxidant properties. However, it can be part of a healthy diet if it is produced with the minimal addition of sugar. This study aimed to evaluate the performance of the FTIR-ATR technique to discriminate the authenticity (concerning the addition of other pulps) and amount of sugar in peach nectars. This technique is usually used in food analysis because it does not require sample preparation, is quick and allows for the determination of several parameters with a single sample aliquot. The nutritional information provided on the labels of 69 samples of 23 different brands of commercial peach juice, was analysed. The differences in the nutritional composition and in the ingredients were determined according to an analysis of the labels. The largest differences observed between the samples were the sugar contents, the percentages of pulp and the addition of other pulps. All samples were analysed by FTIR-ATR equipped with a controlled temperature flow-through cell. The spectral multivariate analysis suggested it was possible to identify differences in the amount of sugar present and identify the presence of fruit pulps other than peach.
The aim of this study was to evaluate the effects of heat-shock and UV-C radiation stress treatments, applied in whole carrots, on the overall quality of fresh-cut carrot cv. Nantes during storage (5º C).
This work aimed to optimize the in vitro multiplication phase of the gore (Pterospartum tridentatum (L. Wilk)).
Só está disponível o resumo.
The morphology and physiology of plants grown in vitro are regulated by various environmental factors such as light, temperature, humidity and carbon dioxide. Light, in its various parameters such as spectral quality, photon flux and photoperiod, is an important factor among these and generally influences the overall growth and development of plants in vitro. Light sources commonly used for in vitro plant culture are fluorescent lamps, although some research and commercial laboratories also use sodium metal or incandescent metal halide lamps. The spectral of those lamps range from 350 to 750 nm and contain blend lights that differentially affect in vitro plant growth. Recently, light emitting diodes (LEDs) have been developed and are nowadays used as an alternative source of fluorescent light for the development of plants both in greenhouses and in vitro culture rooms. In order to test the influence of these two types of light during multiplication phase, a multiplicity experiment was carried out using two species: a chestnut hybrid (Castanea sativa x C. crenata), clone M2 and the prickled broom (Pterospartum tridentatum (L.) Willk.), Malcata ecotype. Two types of light were tested, "cool white" fluorescent light and LED light with blue and red colors. It was found that LED illumination exerted a significant positive effect on the differentiation of shoots in the case of prickled broom (5.6 instead of 4.9 split shoots under fluorescent light). In the parameters of shoot length, we found that this type of lighting favored the elongation in both species. Regarding the parameters of fresh and dry weight, LED lighting caused a greater effect on the chestnut than on prickled broom. Some physiological parameters (chlorophylls, carotenoids and proteins) were also analyzed and showed to be influenced by the type of light during the development of microplants.
Em Portugal, crescem espontaneamente espécies de Lavandula da secção
Stoechas Ging. Estas espécies são consideradas Plantas Aromáticas e Medicinais (PAM)
devido à produção de metabolitos secundários com propriedades terapêuticas e
aromáticas. Devido ao seu elevado polimorfismo e capacidade de hibridação na natureza,
torna-se importante o conhecimento e distinção entre as espécies e subespécies. Apesar
de alguns dos constituintes químicos serem compartilhados entre estas espécies, a
presença de outros e respetivas concentrações são exclusivas de cada uma e, por
conseguinte, a sua aplicação e uso também deve ser diferenciado. De forma a contribuir
para a diferenciação entre espécies e subespécies de Lavandula que crescem na região da
Beira Baixa (BB) recorreu-se aos referenciais morfológicos de Portugal e Península
Ibérica. Através da análise destes referenciais, pode-se concluir que existem alguns
parâmetros morfológicos destacados e/ou diferenciadores entre espécies e subespécies,
salientando-se o tamanho do pedúnculo e espiga e respetiva relação, o tamanho das
brácteas inférteis e a forma das brácteas férteis. Neste trabalho, são apresentados os
resultados da observação da maioria dos parâmetros diferenciadores, em 80 plantas
recolhidas na região da BB. De acordo com os resultados, entre as subespécies, a maioria
dos parâmetros são redundantes e comuns, pelo que a análise morfológica externa da
planta não demonstrou ser suficiente para distinguir as subespécies. Considerando a
evolução natural das espécies e polimorfismo, a integração de outros tipos de análises,
como a análise dos constituintes químicos e/ou estudos genéticos, tornam-se importantes
para a diferenciação das subespécies.
Integrado no Programa Agro, Medida 8.1, Projecto nº 800, foram elaborados
estudos de distribuição e propagação da espécie Thymus mastichina L., existentes
espontaneamente na Beira Interior. Foram avaliadas seis zonas ecológicas distintas
denominadas Vale do Tejo, Beira Interior Sul, Cova da Beira, Beira Interior Norte,
Serra da Estrela e Serra da Gardunha.
Durante dois anos fez-se prospecção no campo em cada zona ecológica e
recolheu-se material vegetal. Realizaram-se ensaios de germinação em laboratório em
condições de temperatura alterna 10º/20ºC (dia) e temperatura constante 23ºC (dia),
com fotoperíodo de 8 e 16 horas/dia, respectivamente. Testou-se ainda a capacidade
germinativa em estufa, na Primavera e efectuaram-se ensaios de enraizamento, com
estacas terminais, em condições de Outono/Inverno e Primavera/Verão.
Na Beira Interior foram encontrados 36 locais onde se verificou a ocorrência de
Thymus mastichina. Em cada zona ecológica onde foram encontrados indivíduos da
espécie em estudo, foi seleccionado um local para recolha de 20 plantas-mãe, que foram
posteriormente instaladas no campo de caracterização/demonstração da ESACB.
Nos ensaios de germinação verificaram-se taxas entre os 80% e 94% em
laboratório e entre os 76% e 84%, em viveiro. Nos ensaios de propagação vegetativa de
estacas terminais obtiveram-se taxas de enraizamento entre os 20% e 100%.
The bioactivity of natural antioxidants from plant extracts is well known. Still, the
effectiveness of these natural antioxidants, namely polyphenols, depends on preserving their stability,
which can be increased by microencapsulation. The aim of this study was to protect natural
antioxidants from the aqueous extract of Portuguese wild herb Pterospartum tridentatum by
encapsulation in alginate hydrogel microbeads. Microbeads were prepared by electrostatic extrusion
technique: plain Ca-alginate microbeads and Ca-alginate microbeads with 10 and 20 mass% of inulin
as a filler substance. Total polyphenol content (TPC) and the radical scavenging activity using ABTS
and DPPH cations were determined. The release studies of polyphenols from microbeads were
performed. The microbeads were analysed by Fourier transform infrared spectroscopy (FTIR),
scanning electron microscopy (SEM) and optical microscopy (OM). Encapsulation efficiency (EE) was
in the range from 49 to 73%. Antioxidant assays and release studies showed that alginate-inulin
microbeads appeared to be suitable dosage forms. The inclusion of inulin contributes to improved
microbeads structure, as well as to nutritional values of food. Thereby, potential applications of these
microbeads could be functional food products, an increasingly valued market.
The morphology and physiology of plants grown in vitro are regulated by various environmental factors such as light, temperature, humidity and carbon dioxide. Light, in its various parameters such as spectral quality, photon flux and photoperiod, is an important factor among these and generally influences the overall growth and development of plants in vitro. Light sources commonly used for in vitro plant culture are fluorescent lamps, although some research and commercial laboratories also use sodium metal or incandescent metal halide lamps. The spectral of those lamps range from 350 to 750 nm and contain blend lights that differentially affect in vitro plant growth. Recently, light emitting diodes (LEDs) have been developed and are nowadays used as an alternative source of fluorescent light for the development of plants both in greenhouses and in vitro culture rooms. In order to test the influence of these two types of light during multiplication phase, a multiplicity experiment was carried out using two species: a chestnut hybrid (Castanea sativa x C. crenata), clone M2 and the prickled broom (Pterospartum tridentatum (L.) Willk.), Malcata ecotype. Two types of light were tested, "cool white" fluorescent light and LED light with blue and red colors. It was found that LED illumination exerted a significant positive effect on the differentiation of shoots in the case of prickled broom (5.6 instead of 4.9 split shoots under fluorescent light). In the parameters of shoot length, we found that this type of lighting favored the elongation in both species. Regarding the parameters of fresh and dry weight, LED lighting caused a greater effect on the chestnut than on prickled broom. Some physiological parameters (chlorophylls, carotenoids and proteins) were also analyzed and showed to be influenced by the type of light during the development of microplants.
A obra é constituída pelos resumos das comunicações apresentadas pelos docentes da Escola Superior Agrária do Instituto Politécnico de Castelo Branco e são referentes aos projetos de investigação nos quais estão envolvidos.
