ABSTRACT Soft corals have been proved to be a rich source of bioactive natural products. This research revealed isolation and structure elucidation of bioactive natural products in the Taiwanese soft coral Junceella juncea. The acetone extract of J. juncea collected in Ken-ting exhibited cytotoxicity against tumor cells. Bioassay- directed fractionation of the EtOAc-layer has resulted in the isolation of five new briaranes, designated juncenolides A-E (1-5) along with a known compound, junceellolide C (6). The structures of compounds 1-6 were determined by the physical methods such as mp¡BIR¡Bmass¡Band optical rotation, and 1D¡B2D NMR spectral analysis, as well as the data reported of the related compounds in publications. In addition, the relative configuration of compound 1 was further confirmed by X-ray single crystal analysis. The basic structures of compounds 1-6 contain a 6/10-membered ring linked with a £^-lactone at C-7/8 and an epoxy group at C-11/20 position. Compound 1 had a chlorine atom at C-6 position with two acetoxyl and an isobutyl groups at C-2, 9, 14 positions. Compounds 2-5 had a cis-cis conjugated double bonds system at C-3, 4, 5, 6 positions, Among them , compound 2 had four acetoxyl groups at C-2, 9, 13, 14 positions, while compounds 3 and 4 had five acetoxyl groups at C-2, 9, 12, 13, 14 positions. In particular, compound 4 had a methoxyl group at C-16 position, which was first found in the briarane-type natural products. Compound 5 had three acetyl and a 3-methylbutyl groups at C-2, 9, 13, 14 positions. In a preliminary pharmacological aporach (cytotoxicity), compound 1 exhibited moderate cytotoxicity against human colon adenocarcinoma (DLD) and oral epidermoid carcinoma (KB-16) cells at a concentration of 3.4 and 5.9 £gg/mL, respectively.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Canola and juncea meals can be used in poultry diets instead of soybean meal. The meals were fed to broilers and turkeys in digestibility trials to measure the apparent metabolizable energy (AMEn). Throughout growth trials, canola and juncea meals were fed at four levels (0, 10, 20 and 30 %) with and without a dietary enzyme cocktail (DEC). This study investigated higher inclusion levels than previously recommended for use in broilers diets. The carcass compositions, fatty acid analysis and liver parameters were measured to investigate the effects of diets on birds. The AMEn of the meals were used in formulating broiler and turkey diets. Growth trials found positive effects of DEC on performance, allowed higher inclusion levels of the meals. No negative effects of diets were observed for liver parameters and carcass compositions. The fatty acid profiles of carcass tissues were improved by increasing levels of canola oil in diets.

Made available in DSpace on 2018-08-01T23:26:40Z (GMT). No. of bitstreams: 1 tese_10705_77 - Esequiel Santos.pdf: 4699017 bytes, checksum: 5fc00aa9ef34cb4c3df7b834203d08c2 (MD5) Previous issue date: 2017-02-23 / Diversos fatores podem interferir no desempenho da fitorremediação de herbicidas no solo, em particular a mineralogia e a atividade microbiana. Com o objetivo de realizar investigações em condições edáficas, utilizando as espécies Canavalia ensiformis e Crotalaria juncea, foi avaliado o efeito da mineralogia e da rizosfera na fitorremediação do herbicida sulfentrazone. Na primeira etapa, os tratamentos foram compostos pela combinação entre três tipos de solos, com texturas diferentes, variando quanto à mineralogia da fração argila dominada por um tipo de mineral (caulinita, hematita e gibbsita) e duas doses de sulfentrazone (0 e 400 g ha-1), dispostos em esquema fatorial 3 x 3 x 2, em DBC, com três repetições. Para o bioensaio, foi semeada uma espécie bioindicadora de resíduo de sulfentrazone no solo, o milheto (Pennisetum glaucum). Os resultados demonstraram que a movimentação do herbicida foi maior no solo caulinítico e a retenção do herbicida foi maior no solo hematítico. A fitorremediação foi mais eficiente no pré-cultivo da C. ensiformis no solo gibbsítico, reduzindo em 28% a carga de sulfentrazone aplicada. Não houve resultado para o solo hematítico. No solo caulinítico, a C. ensiformis reduziu a massa total de sulfentrazone em aproximadamente 11% e a C. juncea em 19%. Na segunda etapa, avaliou-se também a contribuição microbiana rizosférica dessas mesmas espécies na fitorremediação do sulfentrazone. Os tratamentos foram compostos pela combinação de dois solos rizosféricos (feijão de porco e crotalária) e um não-rizosférico com quatro níveis de contaminação pelo herbicida sulfentrazone (0, 200, 400 e 800 g ha-1), dispostos em esquema fatorial 3 x 4. Foram avaliados evolução de CO2, carbono da biomassa microbiana (CBM), quociente metabólico (qCO2), componentes biométricos e fitotoxidade no P. glaucum, em bioensaio e cromatografia líquida do solo. Os resultados indicaram que o cultivo das espécies fitorremediadoras promoveu incremento da atividade microbiana e foi verificado que os perfis genéticos bacterianos foram formados de acordo com a planta e a característica de solo (rizosférico e não rizosférico), ampliando os conhecimentos a respeito das associações entre as plantas e microrganismos.

Oilseed and oilseed meal extracted from members of <i>Brassicaceae</i> release broadspectrum biocidal isothiocyanate when ground and exposed to moisture. The compounds are released when the seed enzyme myrosinase catalyzes the hydrolysis of glucosinolates producing glucose, sulfate, and pesticidal isothiocyanates. Allylisothiocyanate (AITC), the predominant isothiocyanate of <i>Brassica juncea</i>, has broad-spectrum biological activities against plants, animals and fungi. Knowledge of the concentration of AITC arising from a treatment with mustard and AITC toxicity to many target and non-target species is not known. Therefore, factors affecting AITC release and assays of mustard toxicity were conducted. The rate of AITC release from mustard meal was affected by temperature and pH. Current isothiocyanate extraction and quantification methods measure a change in the concentration of glucose (a predominant product of myrosinase-catalysed glucosinolate hydrolysis) to determine myrosinase activity. The objectives of this work were to study: 1) factors affecting myrosinase activity in mustard (<i>Brassica juncea</i>), 2) the effects of AITC on seed germination and 3) the toxicity of AITC and mustard meal.<p> Attempts were made to improve the Herb and Spice Method, the only available industrial method to measure total isothiocyanate production in mustard meal. The effects of a wide range of reaction temperatures (7 to 97°C) and incubation times (0 min to 2 h) on myrosinase-catalyzed conversion of sinigrin (a glucosinolate) to allyl isothiocynate (AITC) were studied. Significant inhibition of enzyme activity was observed at all temperatures over 57°C, and at 97°C no myrosinase activity was found. It was concluded that myrosinase-catalyzed conversion of sinigrin to AITC was a rapid process and detectable amounts of AITC could be found in samples in two min, and that higher temperatures inhibited myrosinase activity. The pH of the reaction mixture significantly affected myrosinase-catalyzed conversion of sinigrin to AITC. A change in pH did not affect the substrate, but severely affected the activity of myrosinase. Furthermore, other compounds viz., boric acid (H3BO3), succinic acid (C2H4(COOH)2),calcium chloride (CaCl2) and ethanol (C2H5OH), were explored for their ability to inhibit myrosinase activity. Calcium chloride and ethanol were particularly effective.<p> It was hypothesized that AITC might act as a plant growth promoter/regulator based on the fact that AITC and ethylene, a plant growth regulator, exhibit structural similarity (R-CH=CH2, where R is -CH2SCN and -H in AITC and ethylene, respectively). Therefore, AITC might act as an ethylene analogue. Ethylene is known to promote seed germination and overcome seed dormancy in a dose- and species-dependent manner.Flax and tomato seeds were used as model systems to test the germination enhancing properties of AITC. It was concluded that AITC promoted flax and tomato seed germination and thus might be used for this application in agricultural practice.<p> An assay was developed for testing AITC toxicity in ground seed by exploring HSP70 expression in <i>Caenorhabditis elegans</i> as a marker of toxicity. <i>C.elegans</i> strain N2 was exposed to different concentrations (0 to 10 ìM) of AITC for 2 h at room temperature. Western blotting with anti-<i>HSP70</i> antibody showed a marked increase in the expression of <i>HSP70</i> protein in a dose-dependent manner. Assays of the expression of <i>HSP70A</i> mRNA by quantitative real time reverse transcriptase (RT) PCR revealed no significant change in the expression of <i>HSP70A</i> mRNA at low concentrations of AITC (< 0.1 ìM). However, treatment with higher concentrations (>1ìM) resulted in four- to five - fold increase in expression of <i>HSP70A</i> mRNA over the control. To understand if mustard toxicity was due to AITC alone, or if other compounds in mustard ground seed affected <i>HSP70</i> transcript production, <i>C. elegans</i> was exposed to AITC or <i>Brassica juncea</i> cv. Arrid ground seed (Arrid is a mustard variety with a lower level of sinigrin (<3 ìM per gram of seed), or both. ELISA revealed increased expression of HSP70 protein in C. elegans treated with AITC + ground seed, but the level of protein was less than that observed with AITC alone. These results indicated that mustard ground seed toxicity was contributed primarily by AITC, and that some ground seed components antagonized AITC toxicity in <i>C. elegans</i>.

Oilseed and oilseed meal extracted from members of <i>Brassicaceae</i> release broadspectrum biocidal isothiocyanate when ground and exposed to moisture. The compounds are released when the seed enzyme myrosinase catalyzes the hydrolysis of glucosinolates producing glucose, sulfate, and pesticidal isothiocyanates. Allylisothiocyanate (AITC), the predominant isothiocyanate of <i>Brassica juncea</i>, has broad-spectrum biological activities against plants, animals and fungi. Knowledge of the concentration of AITC arising from a treatment with mustard and AITC toxicity to many target and non-target species is not known. Therefore, factors affecting AITC release and assays of mustard toxicity were conducted. The rate of AITC release from mustard meal was affected by temperature and pH. Current isothiocyanate extraction and quantification methods measure a change in the concentration of glucose (a predominant product of myrosinase-catalysed glucosinolate hydrolysis) to determine myrosinase activity. The objectives of this work were to study: 1) factors affecting myrosinase activity in mustard (<i>Brassica juncea</i>), 2) the effects of AITC on seed germination and 3) the toxicity of AITC and mustard meal.<p> Attempts were made to improve the Herb and Spice Method, the only available industrial method to measure total isothiocyanate production in mustard meal. The effects of a wide range of reaction temperatures (7 to 97°C) and incubation times (0 min to 2 h) on myrosinase-catalyzed conversion of sinigrin (a glucosinolate) to allyl isothiocynate (AITC) were studied. Significant inhibition of enzyme activity was observed at all temperatures over 57°C, and at 97°C no myrosinase activity was found. It was concluded that myrosinase-catalyzed conversion of sinigrin to AITC was a rapid process and detectable amounts of AITC could be found in samples in two min, and that higher temperatures inhibited myrosinase activity. The pH of the reaction mixture significantly affected myrosinase-catalyzed conversion of sinigrin to AITC. A change in pH did not affect the substrate, but severely affected the activity of myrosinase. Furthermore, other compounds viz., boric acid (H3BO3), succinic acid (C2H4(COOH)2),calcium chloride (CaCl2) and ethanol (C2H5OH), were explored for their ability to inhibit myrosinase activity. Calcium chloride and ethanol were particularly effective.<p> It was hypothesized that AITC might act as a plant growth promoter/regulator based on the fact that AITC and ethylene, a plant growth regulator, exhibit structural similarity (R-CH=CH2, where R is -CH2SCN and -H in AITC and ethylene, respectively). Therefore, AITC might act as an ethylene analogue. Ethylene is known to promote seed germination and overcome seed dormancy in a dose- and species-dependent manner.Flax and tomato seeds were used as model systems to test the germination enhancing properties of AITC. It was concluded that AITC promoted flax and tomato seed germination and thus might be used for this application in agricultural practice.<p> An assay was developed for testing AITC toxicity in ground seed by exploring HSP70 expression in <i>Caenorhabditis elegans</i> as a marker of toxicity. <i>C.elegans</i> strain N2 was exposed to different concentrations (0 to 10 ìM) of AITC for 2 h at room temperature. Western blotting with anti-<i>HSP70</i> antibody showed a marked increase in the expression of <i>HSP70</i> protein in a dose-dependent manner. Assays of the expression of <i>HSP70A</i> mRNA by quantitative real time reverse transcriptase (RT) PCR revealed no significant change in the expression of <i>HSP70A</i> mRNA at low concentrations of AITC (< 0.1 ìM). However, treatment with higher concentrations (>1ìM) resulted in four- to five - fold increase in expression of <i>HSP70A</i> mRNA over the control. To understand if mustard toxicity was due to AITC alone, or if other compounds in mustard ground seed affected <i>HSP70</i> transcript production, <i>C. elegans</i> was exposed to AITC or <i>Brassica juncea</i> cv. Arrid ground seed (Arrid is a mustard variety with a lower level of sinigrin (<3 ìM per gram of seed), or both. ELISA revealed increased expression of HSP70 protein in C. elegans treated with AITC + ground seed, but the level of protein was less than that observed with AITC alone. These results indicated that mustard ground seed toxicity was contributed primarily by AITC, and that some ground seed components antagonized AITC toxicity in <i>C. elegans</i>.

A genetic linkage map of mustard (Brassica juncea) was developed using two double haploid populations produced from crosses between a low erucic cultivar “ZEM1” and two moderate erucic acid lines “Vniimk351” and “Vniimk405” with the use of SSR and SRAP markers. The linkage map of the ZEM1xVniimk351 population included 13 linkage groups with an overall length of 791 cM with an average marker interval of 5.7 cM. The linkage map of the ZEM1xVniimk405 population also contained 13 linkage groups with a distance of 623 cM and an average marker interval of 4.6 cM. Using the linkage maps for the two populations, QTLs were detected for seed oil, protein and fatty acids. QTL analysis for fatty acids indentified QTLs on LG1, 7 and 12 for the ZEM1xVniimk351 population and LG1, 3 and 4 for the ZEM1xVniimk405 population. Analysis for the seed oil and protein content in the ZEM1xVniimk351 population identified 2 QTLs on LG1 and LG4 and 1 QTL on LG1 respectively. The QTL analysis ZEM1xVniimk405 of oil and protein content identified 1 QTL for oil and protein on LG1. The variation of fatty acids was shown to be the result of monogenic inheritance of the FAE1 gene in both populations.

A genetic linkage map of mustard (Brassica juncea) was developed using two double haploid populations produced from crosses between a low erucic cultivar “ZEM1” and two moderate erucic acid lines “Vniimk351” and “Vniimk405” with the use of SSR and SRAP markers. The linkage map of the ZEM1xVniimk351 population included 13 linkage groups with an overall length of 791 cM with an average marker interval of 5.7 cM. The linkage map of the ZEM1xVniimk405 population also contained 13 linkage groups with a distance of 623 cM and an average marker interval of 4.6 cM. Using the linkage maps for the two populations, QTLs were detected for seed oil, protein and fatty acids. QTL analysis for fatty acids indentified QTLs on LG1, 7 and 12 for the ZEM1xVniimk351 population and LG1, 3 and 4 for the ZEM1xVniimk405 population. Analysis for the seed oil and protein content in the ZEM1xVniimk351 population identified 2 QTLs on LG1 and LG4 and 1 QTL on LG1 respectively. The QTL analysis ZEM1xVniimk405 of oil and protein content identified 1 QTL for oil and protein on LG1. The variation of fatty acids was shown to be the result of monogenic inheritance of the FAE1 gene in both populations.

Made available in DSpace on 2014-06-12T23:16:43Z (GMT). No. of bitstreams: 2 arquivo9054_1.pdf: 492584 bytes, checksum: 6cc3078074a14c3528f01574d161cb38 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / A mesoregião do Agreste é caracterizada como a maior produtora de batata (Solanum tuberosum L) no estado da Paraíba. A variabilidade e a escassez de chuvas e a baixa fertilidade do solo, são fatores que limitam a atividade agropecuária nessa região, sendo que, o esterco a única fonte de nutrientes que é incorporada ao solo. Nas propriedades, geralmente não se consegue produzir uma quantidade de esterco suficiente para suprir a demanda das culturas agrícolas. Para minimizar essa limitação da disponibilidade do esterco foi proposta a introdução da adubação verde, com o cultivo e incorporação ao solo da Crotalaria juncea L., seguido ou não da incorporação de esterco. É possível que a aplicação de esterco combinada com o cultivo de cobertura com crotalária possa aumentar a produtividade de batata e contribuir para uma redução dos custos com a compra de esterco, sem comprometer a fertilidade do solo em longo prazo. Sendo assim, a primeira parte do presente trabalho, objetivou quantificar a produtividade da batata e o estoque de nutrientes no solo, ao longo de cinco anos de incorporação de esterco e/ou crotalária em um Neossolo Regolítico no Agreste paraibano. O trabalho foi conduzido anualmente em parcelas de campo de 1996 a 2002 (exceto em 1998 e 1999, devido à insuficiência de chuvas). Os tratamentos aplicados consistiram em: plantio e incorporação da crotalária na época de floração (C), adição de 15 t ha-1 de esterco (E), plantio e incorporação de crotalária + 7,5 t ha-1 de esterco (CE), testemunha sem esterco ou crotalária (T). As concentrações de nutrientes (N, P e K) e o pH do solo tiveram aumentos significativos nos tratamentos E e CE, em relação aos tratamentos C e T, ao longo dos anos de cultivo. Apesar do tratamento E ter proporcionado o maior aumento na concentração de nutrientes do solo, o tratamento CE foi o que levou a uma maior produtividade de tubérculos. Provavelmente, isso ocorreu porque o tratamento CE promoveu uma mineralização mais sincronizada com a demanda de nutrientes da batata durante o ciclo de cultivo. Para testar essa hipótese, na segunda parte do trabalho, em 2003, foram realizados experimentos em campo e casa de vegetação, objetivando avaliar a dinâmica da disponibilidade de nutrientes no solo durante o ciclo de cultivo da batata. No experimento em campo avaliou-se a dinâmica da decomposição e liberação de nutrientes pelo material vegetal e xii esterco incorporado ao solo. Utilizaram-se sacolas plásticas contendo o esterco e os materiais vegetais coletados nas respectivas parcelas experimentais antes da incorporação, as quais foram incorporados ao solo na profundidade de 20 cm. As sacolas foram coletadas quinzenalmente, e determinadas às percentagens de massa e nutrientes remanescentes do material incubado no período de 82 dias de incubação. As perdas de massa e nutrientes foram maiores nos primeiros 30 dias da incubação, para todos os tratamentos aplicados. Ao final do ensaio, as proporções de matéria seca e nutrientes remanescentes foram maiores nos tratamentos E e CE. No experimento em campo também avaliou-se a dinâmica da concentração de nutrientes disponíveis no solo ao longo do período de cultivo da batata. Sendo realizadas coletas quinzenais de solo (0-20 cm) ao longo do ciclo de cultivo da batata. Os teores de P e K extraíveis foi significativamente maiores nos tratamentos E e CE. O teor de N mineral (N-NO3- + N-NH4+) no tratamento E não diferiu do tratamento T, os quais foram significativamente menores que nos tratamentos C e CE nas primeiras semanas após a incorporação, indicando que a incorporação de esterco leva a uma imobilização de N do solo durante o período inicial do ciclo de cultivo da batata. O experimento em casa de vegetação objetivou avaliar a absorção de nutrientes pelo capim buffel de amostras de solo das parcelas de campo. Aos 35 dias, após o transplantio do capim buffel, o tratamento CE levou a maior produção de massa seca e acúmulo de nutrientes na planta. Aos 70 e 105 dias, a produção de matéria seca e acúmulo de nutrientes foi significativamente maior no tratamento E, seguido pelos tratamentos CE, C e T. Os resultados obtidos indicam que o cultivo e a incorporação de crotalária combinada com a incorporação de 7,5 t ha-1 esterco promoveu uma disponibilidade de nutrientes no solo mais equilibrada ao longo do ciclo de cultivo da batata, pois manteve os níveis de nutrientes relativamente altos ao longo de todo o período em relação aos demais tratamentos aplicados. A combinação do esterco com a crotalária é uma prática que pode ser mais recomendável para culturas anuais. Com base nos resultados a aplicação de 15 t ha-1 de esterco demonstrou ser mais recomendável para culturas de ciclo mais longo ou perenes, pois a disponibilização de nitrogênio deu-se de forma mais lenta, porém contínua, ao longo do ciclo de cultivo da batata, além de disponibilizar mais P e K que os demais tratamentos estudados. O cultivo e incorporação somente da crotalária não é recomendável, pois apesar de promover um aumento na disponibilidade de N mineral do solo, no período inicial do cultivo da batata, não repõe o P e o K extraídos do solo com a colheita de tubérculos, podendo levar a diminuição dos teores desses elementos no solo

Made available in DSpace on 2015-03-26T13:36:42Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1139190 bytes, checksum: 7d7600e51fc96aab96c671593415f23b (MD5) Previous issue date: 2011-07-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Arsenic is the more dangerous element to human health. Phytoremediation is an important technology to reduce the antropogenic effect in the environmental contamination, but it is necessary a detailed knowledge of tolerance mechanism, which is the goal of this work. We choose Brassica juncea, tolerant plant to several heavy metals, such as cadmium, and a plant of rapid growth. The arsenate was added to nutritive solution at final concentrations of 10, 50, 200 and 500 &#956;M, and data was collected after 6, 10, 13, 14, 15 and 16 days of exposition. Higher the arsenic in the treatment, higher the level found in leaves, stalk and in roots reach the highest level (5457 mg Kg-1). This amount was 26 and 34 times higher than that found in stalk and leaves, respectively. No alteration in phosphorus level was found at any treatment . This absence of phosphate uptake inhibition seems to have a contribution to the tolerance found in this genotype. In contrast, arsenic concentrations equal or higher than 50 &#956;M were associated with increase in sulphur content in roots in parallel with an increase in total phenol content in these organs, while it reduced sulfur levels in leaves. The two highest doses of arsenate led to the appearance of toxicity symptoms in leaves, characterized by marginal chlorosis and purple coloring in the abaxial faces of old leaves. Despite the highest levels of arsenic in roots, no change in root length and dry weight was detected. In shoot however, we observed reduction in leaf area, leng th and fresh weight in plants treated with 200 and 500 mM arsenate. Additionally, only the highest dose has produced a reduction in net photosynthesis (A) and stomatal conductance (gS) by the 13th day. On the 14th day it was possible to observe the reduction of these parameters in plants treated with 200 mM arsenate. Longer periods in the presence of hight doses allowed us to observe that, besides the reduction in stomatal opening, arsenic could also produce biochemical limitation to photosynthesis, which was associated to reduction in electron transport rate (ETR) and in the quantic efficiency of photosystem II [Y(II)], concomitantly with increase in the level of energy loss as heat [Y(NPQ)]. The second higher dose (200 &#956;M) has not altered the A and other fluorescence parameters, by the 13th day and only negligible effects in leaf area and dry mass in parallel to no effect in roots was observed. Altogether these data support that the genotype of Brassica juncea under study is tolerant to arsenic. Despite of accumulation of high levels of arsenic in roots, no oxidative damage was observed, and no effects in root growth was noted. The fact that high levels of arsenic has occurred in roots, with minor effects in growth indicate the great potential of this plant to be used in phytoremediation as a phytostabilizer. / O arsênio é considerado o elemento mais perigoso para a saúde humana. Fitorremediação é uma importante tecnologia para amenizar o efeito antropogênico na contaminação ambiental, mas para o seu sucesso é necessário a compreensão detalhada dos mecanismos de tolerância de metais pesados, objetivo deste trabalho. A espécie escolhida foi a Brassica juncea, tolerante a vários metais, como cádmio e zinco, e que possui um crescimento rápido. O arsênio foi fornecido a solução nutritiva na forma de arsenato de sódio nas concentrações de 10, 50, 200 e 500 &#956;M, sendo coletados dados aos 6, 10, 13, 14, 15 e 16 dias após a exposição. Quanto maiores os níveis de arsênio presentes no tratamento, maiores os níveis encontrados na planta, havendo um acúmulo de até 5457 mg Kg-1 de As nas raízes expostas a 500 &#956;M de arsenato. Esta quantidade foi 26 e 34 vezes superior aquela observada em caules e folhas, respectivamente. Em nenhum dos tratamentos foram observadas alterações na concentração de fósforo. Esta ausência de inibição de acúmulo de fósforo pode significar a presença de um mecanismo de tolerância à toxidez do arsênio neste genótipo. Em contraste, doses de arsênio iguais ou superiores a 50 &#956;M aumentaram os níveis enxofre nas raízes, em paralelo com um aumento no teor de fenóis, ao passo que reduziu os níveis de enxofre na folha. As duas maiores doses de arsenato levaram ao aparecimento de sintomas de toxidez nas folhas, caracterizados por clorose marginal e coloração arroxeada nas faces abaxiais de folhas velhas. Apesar dos altos níveis de arsênio em raízes, não houve redução no comprimento e na massa seca deste órgão. Na parte aérea por outro lado, foi observada a redução na área foliar, comprimento e massa fresca em plantas tratadas com 200 e 500 &#956;M de arsenato. Adicionalmente observou-se que somente a maior dose reduziu a fotossíntese líquida (A) e condutância estomática (gS) até o 13º dia. A partir do 14º dia já foi possível observar a queda destes parâmetros em plantas tratadas com 200 &#956;M de arsenato. Maiores períodos na presença altas doses de arsenato permitiram observar que alem da redução da abertura estomática, há uma limitação bioquímica contribuindo para a redução da fotossíntese. A diminuição em A esteve associada a limitações na etapa fotoquímica onde ocorreu uma redução na taxa linear de transporte de elétrons (ETR) e na eficiência quântica do fotossistema II [Y(II)], concomitante com o aumento da perda da energia luminosa na forma de calor [Y(NPQ)]. A segunda maior dose (200 &#956;M) não provocou redução em A e nos parâmetros fotoquímicos até o 13º dia, com reduções negligíveis na área e massa foliar, com nenhum efeito no crescimento das raízes. Em conjunto, estes resultados permitem evidenciar que o genótipo de Brassica juncea em estudo possui tolerância aos níveis de arsênio. Apesar de acumular níveis altíssimos de arsênio nas raízes, estas plantas não apresentaram dano oxidativo, nem redução na acumulação de massa seca nas raízes. O fato de que altos níveis de As seja acumulado nas raízes, com efeitos reduzidos no seu crescimento, indica o grande potencial desta espécie para o seu uso na fitorremediação como uma espécie fitoestabilizadora.