Cadmium associates with oxalate in calcium oxalate crystals and competes with calcium for translocation to stems in the cadmium bioindicator Gomphrena claussenii.

Cadmium (Cd) was shown to co-localise with calcium (Ca) in oxalate crystals in the stems and leaves of Cd tolerant Gomphrena claussenii, but Cd binding remained unresolved. Using synchrotron radiation X-ray absorption near edge spectroscopy we demonstrate that in oxalate crystals of hydroponically grown G. claussenii the vast majority of Cd is bound to oxygen ligands in oxalate crystals (>88%; Cd-O-C coordination) and the remaining Cd is bound to sulphur ligands (Cd-S-C coordination). Cadmium binding to oxalate does not depend on the amount of Ca supplied or from which organs the crystals originate (stems and mature leaves). By contrast, roots contain no oxalate crystals and therein Cd is bound predominantly by S ligands. The potential to remove Cd by extraction of Cd-rich oxalate crystals from plant material should be tested in phytoextraction or phytomining strategies.

The mutual restraint effect between the expansion of Alternanthera philoxeroides (Mart.) Griseb and cadmium mobility in aquatic environment.

Alternanthera philoxeroides (Mart.) Griseb is one of the most malignant weeds in its invision habitats. While in the cadmium-contaminated aquatic environment, does A. philoxeroides possess good tolerance and adaptability? To demonstrate the effects of cadmium on A. philoxeroides in the polluted water bodies, a hydroponic stress experiment was conducted over a gradient of Cd concentrations (0, 2.5 and 5mg/l) in triplicate. The seedlings were cultured in a greenhouse and harvested on days 0, 10, 20, 30 and 40, respectively. The results showed the effects of mutual restraint between Cd and A. philoxeroides. The A. philoxeroides seedlings were enriched with large amounts of Cd, and the toxicity of Cd inhibited the rapid growth of A. philoxeroides and induced the rapid degradation of chlorophylls in its tissues. Furthermore, the use of iron plaque effectively immobilized Cd of 1123-2883mg/kg·DW on the root surface, thus it decreased the transferability of Cd in the aquatic environment. Due to its extensive adaptability, good Cd tolerance and the immobilization of Cd predominantly in the roots (the highest Cd concentration enriched was 7588.65±628.90mg/kg·DW in roots). A. philoxeroides effectively restrained the translocation of Cd and partitioned Cd in the roots within water bodies. CAPSULE: The antagonistic effect exists between the invasion of A. philoxeroides and cadmium mobility in aquatic environments.

Chloroplast ultrastructure and thylakoid polypeptide composition are affected by different salt concentrations in the halophytic plant Arthrocnemum macrostachyum.

The effect of different external salt concentrations, from 0 mM to 1030 mM NaCl, on photosynthetic complexes and chloroplast ultrastructure in the halophyte Arthrocnemum macrostachyum was studied. Photosystem II, but not Photosystem I or cytochrome b6/f, was affected by salt treatment. We found that the PsbQ protein was never expressed, whereas the amounts of PsbP and PsbO were influenced by salt in a complex way. Analyses of Photosystem II intrinsic proteins showed an uneven degradation of subunits with a loss of about 50% of centres in the 0 mM NaCl treated sample. Also the shape of chloroplasts, as well as the organization of thylakoid membranes were affected by NaCl concentration, with many grana containing few thylakoids at 1030 mM NaCl and thicker grana and numerous swollen thylakoids at 0 mM NaCl. The PsbQ protein was found to be depleted also in thylakoids from other halophytes.

Produção da fáfia [Pfaffia glomerata (Spreng. ) Pedersen] com cama-de-frango e fósforo incorporados ao solo / Yield of fáfia [Pfaffia glomerata (Spreng. ) Pedersen] with chicken manure, with or without the use of phosphorus incorporated to the soil

Objetivou-se com este trabalho avaliar o efeito da incorporação ao solo de cama-de-frango e de fósforo sobre o crescimento e a produção da fáfia. Os tratamentos foram cinco doses de cama-de-frango semidecomposta (0, 5, 10, 15 e 20 t ha-1), com e sem o uso de fósforo (200 kg ha-1 de P2O5, na forma de superfosfato triplo), arranjados em esquema fatorial 5 x 2, no delineamento experimental blocos casualizados, com quatro repetições. As alturas das plantas variaram em função das doses da cama-de-frango, sendo maiores (138,50 cm) sob 20 t ha-1. As produções de massas frescas e secas de folhas, caules e raízes foram influenciadas significativamente pela interação cama-de-frango e fósforo. As maiores produções de massa fresca e seca de folhas (597 kg ha-1 e 100 kg ha-1, respectivamente) foram obtidas com a dose de 20 t ha-1 de cama-de-frango, sem o uso de fósforo. Para caules, as maiores produções de massa fresca e seca (7.757 kg ha-1 e 2.633 kg ha-1, respectivamente) foram obtidas com a dose de 20 t ha-1 de cama-de-frango, com o uso de fósforo. As maiores produções de massa fresca e seca de raízes (9.065 kg ha-1 e 377 kg ha-1, respectivamente) foram obtidas com a dose de 20 t ha-1 de cama-de-frango, sem o uso de fósforo. Os teores médios de N, P e K das folhas foram de 8,60; 0,88 e 4,46 g kg-1, respectivamente. Os teores de Ca e Mg foram máximos (7,56 e 5,12 g kg-1, respectivamente) com o uso de 20 t ha-1 de cama-de-frango, independente do uso de P. Nas raízes os teores médios de N, P e Mg foram de 2,74; 0,27 e 0,96 g kg-1, respectivamente. O teor de K reduziu linearmente com as doses de cama-de-frango e o de Ca foi máximo com o uso de 20 t ha-1. Para se obter maiores produções de massas frescas e secas de folhas e raízes, as plantas de fáfia devem ser cultivadas com cama-de-frango (20 t ha-1) incorporada ao solo, sem necessidade de adição de fósforo.

The aimed of this study was to evaluate the effect of of chicken manure and phosphorus incorporated to the soil on growth and yield of fáfia. Treatments were five doses of chicken manure (0, 5, 10, 15 and 20 t ha-1), with and without the use of phosphorus (200 kg ha-1 of P2O5, in triple superphosphate form), arranged in 5 x 2 factorial scheme in randomized block design with four replications. Plant heights varied as a function of chicken manure doses, which the highest (138.50 cm) under 20 t ha-1. Yields of fresh and dried weight of leaves, stems and roots were influenced significantly by the interaction chicken manure x phosphorus. The highest yields of fresh and dried leaves (597 kg ha-1 and 100 kg ha-1, respectively) were obtained with the dose of 20 t ha-1 of chicken manure, without the use of phosphorus. For stems, the highest yields of fresh and dried weight (7.757 kg ha-1 and 2.633 kg ha-1, respectively) were obtained with the dose of 20 t ha-1 of chicken manure, with the use of phosphorus. The highest yields of fresh and dried weight of roots (9.065 kg ha-1 and 377 kg ha-1, respectively) were obtained with the dose of 20 t ha-1 of chicken manure, without the use of phosphorus. Average contents of N, P and K of leaves were 8.60; 0.88 and 4.46 g kg-1, respectively. Contents of Ca and Mg were maximum (7.56 and 5.12 g kg-1, respectively) with the use of 20 t ha-1 of chicken manure, independent on the use of phosphorus. In roots, average contents of N, P and Mg were 2.74, 0.27 and 0.96 g kg-1, respectively. K content reduced linearly with chicken manure doses and of Ca was maximum with the use of 20 t ha-1. For obtaining the highest yields of fresh and dried weight of leaves and roots, the fáfia plants must be grown with chicken manure (20 t ha-1) incorporated to the soil within the use of phosphorus.

Produção de biomassa e absorção de N e P pela Pfaffia glomerata (Spreng. ) Pedersen em função de doses de N e P em condições de casa de vegetação / Biomass production and N and P uptake by Pfaffia glomerata (Spreng. ) Pedersen according to N and P levels under greenhouse conditions

Com objetivo de avaliar a produção de biomassa e absorção de N e P pela Pfaffia glomerata em função de doses de N e P, foi realizado o presente trabalho, em casa de vegetação, utilizando como substrato Latossolo Vermelho distroférrico, coletado na camada de 0 - 20 cm. O delineamento foi inteiramente casualizado com três repetições e os tratamentos foram dispostos em esquema fatorial 5 x 5, sendo cinco doses de N (0, 125, 250, 375 e 500 mg vaso-1) e cinco doses de P (0, 125, 250, 375 e 500 mg vaso-1). As variáveis analisadas foram altura de plantas, massa fresca e seca da parte aérea e radicular e teores de N e P na parte aérea e radicular. Os resultados evidenciaram efeito interativo do N e P, em todas as variáveis analisadas, exceto com relação ao teor de P na parte aérea e radicular. A produção de biomassa e absorção de N e P pela Pfaffia glomerata foi influenciada pelas doses de N e P utilizadas no experimento e para a produtividade ótima das características avaliadas, as doses de N variaram entre 42,9 e 346,01 mg vaso-1 e as doses de P entre os valores de 72,02 e 500 mg vaso-1.

With the aim of evaluating biomass production and N and P uptake by Pfaffia glomerata according to N and P levels, the present study was carried out in a greenhouse, using as substrate Oxisol collected at the layer 0 - 20 cm. Experimental design was completely randomized, with three replicates and treatments arranged in 5 x 5 factorial arrangement, with five N levels (0, 125, 250, 375 and 500 mg pot-1) and five P levels (0, 125, 250, 375 and 500 mg pot-1). The assessed parameters were plant height, shoot and root fresh and dry matter, and N and P levels in shoot and roots. Results evidenced an interactive effect of N and P for all studied variables, except for N and P levels in shoot and roots. Biomass production and N and P uptake by Pfaffia glomerata were influenced by the N and P levels used in the experiment, whereas the optimal productivity was obtained with N levels ranging between 42.9 and 346.01 mg pot-1 and P levels between 72.02 and 500 mg pot-1.

Tolerance of combined submergence and salinity in the halophytic stem-succulent Tecticornia pergranulata.

BACKGROUND AND AIMS: Habitats occupied by many halophytes are not only saline, but are also prone to flooding. Few studies have evaluated submergence tolerance in halophytes. METHODS: Responses to submergence, at a range of salinity levels, were studied for the halophytic stem-succulent Tecticornia pergranulata subsp. pergranulata (syn. Halosarcia pergranulata subsp. pergranulata). Growth and total sugars in succulent stems were assessed as a function of time after submergence. Underwater net photosynthesis, dark respiration, total sugars, glycinebetaine, Na(+), Cl(-) and K(+), in succulent stems, were assessed in a NaCl dose-response experiment. KEY RESULTS: Submerged plants ceased to grow, and tissue sugars declined. Photosynthesis by succulent stems was reduced markedly when underwater, as compared with in air. Capacity for underwater net photosynthesis (P(N)) was not affected by 10-400 mM NaCl, but it was reduced by 30 % at 800 mM. Dark respiration, underwater, increased in succulent stems at 200-800 mM NaCl, as compared with those at 10 mM NaCl. On an ethanol-insoluble dry mass basis, K(+) concentration in succulent stems of submerged plants was equal to that in drained controls, across all NaCl treatments. Na(+) and Cl(-) concentrations, however, were elevated in stems of submerged plants, but so was glycinebetaine. Submerged stems increased in succulence, so solutes would have been 'diluted' on a tissue-water basis. CONCLUSIONS: Tecticornia pergranulata tolerates complete submergence, even in waters of high salinity. A 'quiescence response', i.e. no shoot growth, would conserve carbohydrates, but tissue sugars still declined with time. A low K(+) : Na(+) ratio, typical for tissues of succulent halophytes, was tolerated even during prolonged submergence, as evidenced by maintenance of underwater P(N) at up to 400 mM NaCl. Underwater P(N) provides O(2) and sugars, and thus should enhance survival of submerged plants.

The role of citric acid in cadmium and nickel uptake and translocation, in Halimione portulacoides.

Some plants have high ability to absorb heavy metals in high concentrations. In this study, Halimione portulacoides was tested in conjunction with citric acid, in order to evaluate the possible use of this plant in phytoremediation processes in salt marshes. Two different concentrations of chelator were used combined with two heavy metal concentrations. When 25microM of citric acid was applied, Cd uptake and translocation was enhanced while for Ni these processes were almost inhibited. Increasing citric acid concentration to 50microM, Ni absorption decreased by the roots while for Cd there was still an increase in root uptake. Analysing translocation with this concentration of chelator, a decreased metal content in the upper organs for both metals was observed. While for Cd an optimal concentration of 25microM of citric acid was observed for phytoremediative processes, for nickel neither concentrations of chelator showed advantages for application in this remediative method.

Comparative study of antibacterial and antifugal activity of callus culture and adult plants extracts from Alternanthera maritima (Amaranthaceae)

Neste estudo procedeu-se a avaliação da atividade antibacteriana e antifúngica dos extratos brutos de Alternanthera maritima (Amaranthaceae) planta in natura de duas coletas distintas e obtidos por cultura de células buscando-se averiguar a manutenção da atividade antimicrobiana dos extratos obtidos da planta in vivo e in vitro. A ação antibacteriana e antifúngica foi determinada pelo método de difusão em ágar (técnica do poço) utilizando-se trinta cepas de microrganismos indicadores (bactérias Gram-positivas e Gram-negativas, leveduras e dermatófitos). Todos os extratos obtidos com solventes orgânicos avaliados apresentaram-se bioativos com halos de inibição de 6 a 20 mm. Os extratos da planta in natura das duas coletas (Restinga de Marica (RJ), verão de 1995 e 1998) inibiram o desenvolvimento de diferentes microrganismos (bactérias, leveduras e dermatófitos). Os extratos obtidos da cultura de calos desenvolvidos em duas condições de cultivo diferentes, também se mantiveram bioativos. Assim, os resultados obtidos encorajam a realização de novos estudos com esta espécie vegetal para se determinar quais as substâncias presentes nos extratos e que contribuem para a atividade biológica, como também para entender seu mecanismo de ação e avaliar sua toxicidade, visando uma possível aplicação farmacêutica.