The physiological quality of cotton cultivar seeds (Gossypium hirsutum var. latifolium L.) was evaluated in laboratory by the simulation of water potentials with polyethyleneglycol-6000 (0.0; -0.2; -0.4; -0.6; -0.8 and -1.0 MPa), at 25ºC using germitest paper as substrate. A completely randomized design in a 4 × 6 factorial scheme with four replications of 50 seeds each was used. The studied variables were: germination percentage, first count of germination, germination velocity index, accelerated aging in water, electrical conductivity, humidity, vigor classification, radicle length and radicle/shoot length ratio. The effect of water stress on seed viability and on plantlet vigor was severe at potentials below -0.4 MPa. The 'CNPA 187 8H' cultivar was the least sensitive to the tested osmotic potentials, both in terms of germination and of vigor. The 'BRS-201' cultivar was mostly affected by the viability and vigor tests under water deficit conditions. Differential viability and vigor between cultivars were observed under the water stress levels. Key words: Gossypium hirsutum var. latifolium L., PEG-6000, vigor, water potential Germinação de sementes de cultivares de algodoeiro sob estresse hídrico induzido por polietilenoglicol-6000RESUMO: A qualidade fisiológica de sementes de cultivares de algodoeiro (Gossypium hirsutum var. latifolium L.) foi avaliada em laboratório pela simulação de potenciais hídricos com polietilenoglicol-6000 (0,0; -0,2; -0,4; -0,6; -0,8 e -1,0 MPa), na temperatura de 25ºC, em substrato papel germitest. O delineamento utilizado foi o inteiramente casualizado, em esquema fatorial 4 × 6, com quatro repetições de 50 sementes. As variáveis estudadas foram: porcentagem de germinação, primeira contagem da germinação e índice de velocidade de germinação, envelhecimento acelerado em água, condutividade elétrica, umidade, classificação de vigor (plântulas normais, fortes ou fracas), comprimento de radícula e relação radícula/parte aérea. O efeito do estresse hídrico na viabilidade das sementes e no vigor das plântulas foi severo a partir de -0.4 MPa. O cultivar CNPA 187 8H foi o menos sensível aos níveis de potenciais osmóticos testados tanto em termos de germinação, como de vigor. O cultivar BRS-201 foi o mais afetada nos testes de viabilidade e vigor em condições de déficit hídrico. Observou-se comportamento diferenciado em relação à viabilidade e vigor em diferentes níveis de estresse hídrico simulado por polietilenoglicol-6000. Palavras-chave: Gossypium hirsutum var. latifolium L., PEG-6000, vigor, potencial hídrico
ABSTRACT. The objective of this work was to evaluate the cytotoxic effect of the food dyes erythrosine, brilliant blue and red 40 on the cell cycle of Allium cepa L. Each dye was evaluated at doses of 0.4 and 4.0 ml, at exposure times of 24 and 48 hours, in onion root tip cells. Cells and the presence of chromosomal aberrations were analyzed throughout the whole cell cycle, totaling 5,000 cells for each group of bulbs. The mitotic index was calculated and the statistical analysis was conducted through the Chi-square test (p < 0.05). From the obtained results, it was verified that the food additives erythrosine and brilliant blue were not cytotoxic to the cells of the test system. However, the red 40 dye, at the two evaluated doses and the two exposure times used in this bioassay have promoted a significant reduction in cell division and induced the emergence of anaphasic and telophasic bridge aberrations and micronucleated cells. Additional cytotoxicity studies should be conducted to add information to these and other previously obtained results in order to evaluate, with property, the action of these three dyes on a cellular level.Keywords: food additive, dye toxicity, Allium cepa.Citotoxicidade dos corantes alimentares erythrosine (E-127), azul brilhante (E-133) e red 40 (E-129) em sistema-teste vegetal RESUMO. Este trabalho teve por objetivo avaliar o efeito citotóxico dos corantes alimentares eritrosina, azul brilhante e vermelho 40 sobre o ciclo celular de Allium cepa L. Cada corante foi avaliado nas doses de 0,4 e 4,0mL, nos tempos de exposição de 24 e 48h, em células meristemáticas de raízes de cebolas. Foram analisadas células em todo o ciclo celular e a presença de aberrações cromossômicas, totalizando 5.000 células para cada grupo de bulbos. Calculou-se o índice mitótico e a análise estatística foi feita por meio do teste Qui-quadrado (p < 0,05). A partir dos resultados obtidos, verificou-se que os aditivos alimentares eritrosina e azul brilhante não foram citotóxicos às células do sistema-teste em questão. Já o corante vermelho 40, nas duas doses avaliadas e nos dois tempos de exposição estipulados para este bioensaio, promoveu redução significativa da divisão celular e induziu o aparecimento de aberrações dos tipos ponte anafásica, ponte telofásica e célula micronucleada. Estudos adicionais de citotoxicidade devem ser conduzidos para se somar a estes para assim avaliar, com propriedade, a ação destes três corantes em nível celular.Palavras-chave: aditivo alimentar, toxicidade de corante, Allium cepa.
In general, tropical rivers have a great impact on human activities. Bioaccumulation of toxins is a worldwide problem nowadays and has been, historically, overlooked by the supervisory authorities. This study evaluated cytogenotoxic effects of Guaribas river (a Brazilian river) water during dry and rainy seasons of 2014 by using the Allium cepa test system. The toxicogenetic variables, including root growth, mitotic index, and chromosomal aberrations, were analyzed in meristematic cells of A. cepa exposed to water samples taken from the up-, within, and downstream of the city Picos (state: Piauí). The physical-chemical parameters were also analyzed to explain water quality and possible anthropogenic action. Additionally, the presence of heavy metals was also analyzed to explain water quality and possible damaging effects on eukaryotic cells. The results suggest that the river water exerted cytotoxic, mutagenic, and genotoxic effects, regardless of the seasons. In addition, Guaribas river presented physico-chemical values outside the Brazilian laws, which can be a characteristic of human pollution (domestic sewage, industrial, and local agriculture). The genetic damage was positively correlated with higher levels of heavy metals. The pollution of the Guaribas river water may link to the chemical contamination, including the action of heavy metals and their impacts on genetic instability in the aquatic ecosystem. In conclusion, necessary steps should be taken into account for further toxicogenetic studies of the Guaribas river water, as it has an influence in human health of the same region of Brazil.
ResumoNeste estudo, avaliou-se a ação do suco de noni sobre as células meristemáticas de raízes de Allium cepa, em duas concentrações, 0,18 e 0,36 mg/mL, com os tempos de exposição de 24 e 48 h. Para cada concentração se utilizou um grupo de 5 bulbos de cebolas, que primeiramente foram inseridos em água destilada e, em seguida, transferidos para suas respectivas concentrações. As radículas foram coletadas e ixadas em ácido acético (3:1) por 24 h. As lâminas foram preparadas pela técnica de esmagamento, e coradas com orceína acética a 2%. Foram analisadas células em todo ciclo celular, totalizando 5.000 para cada controle e tempo de exposição. Os índices mitóticos calculados foram submetidos à análise estatística de qui-quadrado (p < 0,05). Veriicou-se que ambas as concentrações, inclusive a menor, considerada ideal para consumo, aumentou de forma signiicativa o índice mitótico das células meristemáticas de raízes de cebola. Portanto, nas condições analisadas, ambas as concentrações testadas do suco de noni promoveram alteração na divisão celular desse sistema-teste vegetal.Palavras-chave: Divisão celular; Noni; Planta medicinal; Raízes de Allium cepa AbstractAction of the juice from the fruit of Morinda citrifolia L. on cells of the plant test system. In this study, we evaluated the action of noni juice on the meristematic cells of Allium cepa roots, at two concentrations, 0.18 and 0.36 mg/mL, with the exposure times of 24 and 48 h. For each concentration, we used a group of 5 onion bulbs, which were irst embedded in distilled water and, then, transferred to their respective concentrations. The radicles were collected and ixed in acetic acid (3:1) for 24 hours. The root tips were collected and ixed in acetic acid (3:1) for 24 h. The slides were prepared through the crushing technique, and stained with 2% acetic orcein. Cells were analyzed throughout the cell cycle, totaling 5,000 for each control and exposure time. The mitotic indices calculated underwent chi-square (p < 0.5) statistical analysis. We found out that both concentrations, including the lowest, regarded as ideal for consumption, signiicantly increased the mitotic index of meristematic cells of onion roots. Therefore, under the analyzed conditions, both tested concentrations of noni juice have promoted change in the cell division of this plant test system.
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