This work aimed to develop a protocol for the in vitro establishment, multiplication, rooting and ex vitro acclimatization of Mimosa pudica L., a species used in folk medicine and with pharmacological activity. Aseptic cultures were established from seeds inoculated in MS medium, without growth regulators, followed by an in vitro stabilization phase in culture medium supplemented with 2.22 μM BAP. The cultures were transferred to MS medium supplemented with different cytokinins, combined or not with an auxin, aiming its large-scale propagation. The culture medium supplemented with 5 µM BAP plus 0.5 µM NAA provided the highest multiplication rate and top quality plantlets. The combination of 0.6 µM TDZ plus 0.05 µM NAA resulted in higher multiplication rates than in response to combination of BAP plus NAA, although the subsequent maintenance of the cultures in a medium without growth regulators has resulted in low regenerative response. In vitro rooting of micro-cuttings was high even in the absence of auxins. Over 90% of plantlets transferred to the greenhouse survived after the acclimatization phase. Acclimatized plants presented normal vegetative and reproductive development. The procedures established in the present study allow a massive production of M. pudica plants for further pharmacological studies.

In this study, the activities of antioxidant enzymes, photosynthetic pigments, proline and carbohydrate contents in Pitcairnia encholirioides under ex vitro conditions of water deficit were evaluated. Results show that plants under progressive water stress, previously in vitro cultured in media supplemented with 30 g L-1 sucrose and GA3, accumulated more proline and increased peroxidase (POD) activity and the contents of photosynthetic pigments and carbohydrates. For plants previously in vitro cultured with 15 g L-1 sucrose and NAA, no differences were found for proline content and there were reductions in activities of peroxidase (POD), catalase (CAT) and poliphenoloxidase (PPO), and in contents of carbohydrates, with progress of ex vitro water deficit. After rehydration, plants showed physiological recovery, with enzymatic activities and contents of metabolites similar to those found in the controls not submitted to dehydration, regardless of the previous in vitro culture conditions. These results show that micropropagated P. encholirioides has high tolerance to dehydration once in ex vitro conditions, which can ensure the survival of plants from tissue culture when transferred to its natural environment, emphasizing the importance of such biotechnology for the propagation of endangered species.

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In this work, the physiological responses and leaf uptake of Cu, Cr, Fe, Pb and Zn were evaluated during the initial growth of Italian ryegrass with addition of urban sewage sludge (LE) and its relationship with the foliar levels of organic acids (OA) obtained by a simple extraction method, using only water as solvent and with less extraction time. The minimum and maximum contents (mg kg-1) found in Italian ryegrass leaves after 14 days in contact with the sludge (Cu: 12.6-21.2; Cr: 26.9-130; Fe: 395.9-6171 and Zn: 138-1190) indicated the bioaccumulation potential of the species. Only Pb concentration was below the limit of detection (LD) and quantification (LQ). Citric acid (1,966 mg g-1) and malic acid (0.957 mg g-1) were successfully quantified, along with positively identified peaks of aspartic acid, indicating that those AO might be related to the nutritional behavior of the species, particularly in the regulation of the uptake of elements harmful to metabolism. Based on the stability constants of malic acid for the formation of organo-metallic complexes (Kest: 3.40 for Cu, 2.75 for Pb and 2.00 for Zn), in addition to interaction studies of carboxyl groups with metal ions, especially the citrate group, it can be suggested that the exudation of citric, malic and aspartic acids promotes uptake and retention of metals, thus facilitating the adaptation of the species in anthropic systems. It is concluded that Italian ryegrass responds positively to the application of LE, however accumulating metals at levels potentially harmful. Neste trabalho foi avaliado as respostas fisiológicas e a absorção foliar de Cu, Cr, Fe, Pb e Zn durante o cultivo inicial do azevém anual com adição de lodo de esgoto (LE) e suas relações com os teores foliares de ácidos orgânicos de baixo massa molecular (AO), obtidos por um método de extração simples, utilizando apenas água como solvente e com menor tempo de extração. Os teores mínimo e máximo (mg kg-1) encontrados em folhas de azevém anual após 14 dias em contato com o lodo (Cu: 12,6-21,2; Cr: 26,9-130; Fe: 395,9-6171 e Zn: 138-1190) indicaram o potencial de bioacumulação da espécie. Apenas a concentração de Pb ficou abaixo do limite de detecção (LD) e quantificação (LQ). Foram quantificados os ácido cítrico (1.966 mg g-1) e málico (0,957 mg g-1) nas folhas e identificados picos de ácido aspártico, indicando que os mesmos podem estar relacionados ao comportamento nutricional da espécie, particularmente na promoção ou inibição da absorção de elementos ao metabolismo. Com base nas constantes de estabilidade do ácido málico para a formação de complexos organo-metálicos (Kest: 3,40 para o Cu; 2,75 para o Pb e 2,00 para o Zn), além de estudos de interação de grupos carboxilados com íons metálicos, em especial o grupo citrato, pode-se sugerir que a exsudação dos ácidos cítrico, málico e aspártico promove a absorção e retenção de metais e facilita a adaptação da espécie em sistemas antropizados.