• Impact of copper nanoparticles and ionic copper exposure on wheat (Triticum aestivum L.) root morphology and antioxidant response.

      Zhang, Zhenyan; Ke, Mingjing; Qu, Qian; Peijnenburg, W J G M; Lu, Tao; Zhang, Qi; Ye, Yizhi; Xu, Pengfei; Du, Benben; Sun, Liwei; et al. (2018-04-28)
      Copper nanoparticles (nCu) are widely used in industry and in daily life, due to their unique physical, chemical, and biological properties. Few studies have focused on nCu phytotoxicity, especially with regard to toxicity mechanisms in crop plants. The present study examined the effect of 15.6 μM nCu exposure on the root morphology, physiology, and gene transcription levels of wheat (Triticum aestivum L.), a major crop cultivated worldwide. The results obtained were compared with the effects of exposing wheat to an equivalent molar concentration of ionic Cu (Cu2+ released from CuSO4) and to control plants. The relative growth rate of roots decreased to approximately 60% and the formation of lateral roots was stimulated under nCu exposure, possibly due to the enhancement of nitrogen uptake and accumulation of auxin in lateral roots. The expression of four of the genes involved in the positive regulation of cell proliferation and negative regulation of programmed cell death decreased to 50% in the Cu2+ treatment compared to that of the control, while only one gene was down-regulated to about half of the control in nCu treatment. This explained the decreased root cell proliferation and higher extent of induced cell death in Cu2+- than in nCu-exposed plants. The increased methane dicarboxylic aldehyde accumulation (2.17-fold increase compared with the control) and decreased antioxidant enzyme activities (more than 50% decrease compared with the control) observed in the Cu2+ treatment in relation to the nCu treatment indicated higher oxidative stress in Cu2+- than in nCu-exposed plants. Antioxidant (e.g., proline) synthesis was pronouncedly induced by nCu to scavenge excess reactive oxygen species, alleviating phytotoxicity to wheat exposed to this form of Cu. Overall, oxidative stress and root growth inhibition were the main causes of nCu toxicity.
    • Insights into the transcriptional responses of a microbial community to silver nanoparticles in a freshwater microcosm.

      Lu, Tao; Qu, Qian; Lavoie, Michel; Pan, Xiangjie; Peijnenburg, W J G M; Zhou, Zhigao; Pan, Xiangliang; Cai, Zhiqiang; Qian, Haifeng (2020-03-01)
      Silver nanoparticles (AgNPs) are widely used because of their excellent antibacterial properties. They are, however, easily discharged into the water environment, causing potential adverse environmental effects. Meta-transcriptomic analyses are helpful to study the transcriptional response of prokaryotic and eukaryotic aquatic microorganisms to AgNPs. In the present study, microcosms were used to investigate the toxicity of AgNPs to a natural aquatic microbial community. It was found that a 7-day exposure to 10 μg L-1 silver nanoparticles (AgNPs) dramatically affected the structure of the microbial community. Aquatic micro eukaryota (including eukaryotic algae, fungi, and zooplankton) and bacteria (i.e., heterotrophic bacteria and cyanobacteria) responded differently to the AgNPs stress. Meta-transcriptomic analyses demonstrated that eukaryota could use multiple cellular strategies to cope with AgNPs stress, such as enhancing nitrogen and sulfur metabolism, over-expressing genes related to translation, amino acids biosynthesis, and promoting bacterial-eukaryotic algae interactions. By contrast, bacteria were negatively affected by AgNPs with less signs of detoxification than in case of eukaryota; various pathways related to energy metabolism, DNA replication and genetic repair were seriously inhibited by AgNPs. As a result, eukaryotic algae (mainly Chlorophyta) dominated over cyanobacteria in the AgNPs treated microcosms over the 7-d exposure. The present study helps to understand the effects of AgNPs on aquatic microorganisms and provides insights into the contrasting AgNPs toxicity in eukaryota and bacteria.
    • Offspring toxicity of silver nanoparticles to Arabidopsis thaliana flowering and floral development.

      Ke, Mingjing; Li, Yan; Qu, Qian; Ye, Yizhi; Peijnenburg, W J G M; Zhang, Zhenyan; Xu, Nuohan; Lu, Tao; Sun, Liwei; Qian, Haifeng (2020-03-15)
    • Phytotoxic effects of silver nanoparticles and silver ions to Arabidopsis thaliana as revealed by analysis of molecular responses and of metabolic pathways

      Ke, Mingjing; Qu, Qian; Peijnenburg, W.J.G.M.; Li, Xingxing; Zhang, Meng; Zhang, Zhenyan; Lu, Tao; Pan, Xiangliang; Qian, Haifeng (2018-12)
    • Rhizosphere Microbiome Assembly and Its Impact on Plant Growth.

      Qu, Qian; Zhang, Zhenyan; Peijnenburg, W J G M; Liu, Wanyue; Lu, Tao; Hu, Baolan; Chen, Jianmeng; Chen, Jun; Lin, Zhifen; Qian, Haifeng (2020-05-06)