The spatial pattern distribution of plant hormones in response to aluminum (Al) toxicity in roots remains to be shown. This study was performed to assess the root hormonal accumulation and gene expression in response ...The spatial pattern distribution of plant hormones in response to aluminum (Al) toxicity in roots remains to be shown. This study was performed to assess the root hormonal accumulation and gene expression in response to Al toxicity in five transgenic miniature dwarf tomatoes cv. Micro-Tom (MT). MT and MT transgenics to acid indole acetic, cytokinin, gibberellin, abscisic acid and ethylene were cultivated in nutrient solutions containing different Al concentrations. Root growth elongation was measured and cellular damage was visualized by staining Evans’s blue. The GUS reporter gene staining technique was used to visualize hormonal changes in MT apex root tissues. Data indicated that the MT is sensitive to Al that induced significant growth inhibition and cellular damage. Al concentration of 27 μM was significantly toxic, inducing root apex darkening and inhibition of root development. The qualitative evaluation of GUS reporter gene expression showed intense crosstalk among all hormones studied, underscoring the complexity of signaling induced by Al in apex roots. Results point out to a major understanding of the hormonal signaling in response to Al toxicity, which may induce a change of root growth and architecture with growth inhibition and cell constraints modulated by all different hormones evaluated.展开更多
Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide（MgO） particles are being utilized in different fields...Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide（MgO） particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano-and microparticles（NPs and MPs） at a range of exposure concentrations（12.5, 25, 50, and100 μg/m L）. The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index（MI） when compared to control cells and the effect was more significant for NPs than MPs（at p 〈 0.05）. Comet analysis revealed that the Deoxyribonucleic acid（DNA） damage in terms of percent tail DNA ranged from 6.8–30.1 over 12.5–100 μg/m L concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.展开更多
文摘The spatial pattern distribution of plant hormones in response to aluminum (Al) toxicity in roots remains to be shown. This study was performed to assess the root hormonal accumulation and gene expression in response to Al toxicity in five transgenic miniature dwarf tomatoes cv. Micro-Tom (MT). MT and MT transgenics to acid indole acetic, cytokinin, gibberellin, abscisic acid and ethylene were cultivated in nutrient solutions containing different Al concentrations. Root growth elongation was measured and cellular damage was visualized by staining Evans’s blue. The GUS reporter gene staining technique was used to visualize hormonal changes in MT apex root tissues. Data indicated that the MT is sensitive to Al that induced significant growth inhibition and cellular damage. Al concentration of 27 μM was significantly toxic, inducing root apex darkening and inhibition of root development. The qualitative evaluation of GUS reporter gene expression showed intense crosstalk among all hormones studied, underscoring the complexity of signaling induced by Al in apex roots. Results point out to a major understanding of the hormonal signaling in response to Al toxicity, which may induce a change of root growth and architecture with growth inhibition and cell constraints modulated by all different hormones evaluated.
基金the Director IICT, Hyderabad for providing funds and facility to execute this study
文摘Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide（MgO） particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano-and microparticles（NPs and MPs） at a range of exposure concentrations（12.5, 25, 50, and100 μg/m L）. The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index（MI） when compared to control cells and the effect was more significant for NPs than MPs（at p 〈 0.05）. Comet analysis revealed that the Deoxyribonucleic acid（DNA） damage in terms of percent tail DNA ranged from 6.8–30.1 over 12.5–100 μg/m L concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.
