Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou, 510631, China.
Ecotoxicology. 2020 Sep;29(7):959-972. doi: 10.1007/s10646-020-02236-x. Epub 2020 Jun 7.
Ionic lead (Pb) in the environment has accumulated due to anthropogenic activities, causing a potential threat to plants and plant consumers. We conducted this study to reveal the molecular mechanism of Pb stress response in plants. The effects of Pb (5.0 and 15.0 μM) on mitosis, DNA replication, gene expression and proteins in root-tip cells of Allium cepa var. agrogarum L. were addressed. The results indicated that root growth was inhibited dramatically in Pb treatment groups. Chromosomal aberrations were observed and the mitotic index decreased during Pb treatments at different concentrations. The accumulation of reactive oxygen species (ROS) in onion roots was induced by Pb stress. Pb increased DNA damage and suppressed cell cycle progression. The above toxic effects got more serious with increasing Pb concentration and prolonging exposure time. A total of 17 proteins were expressed differentially between control and Pb exposure groups. Under Pb treatment, the decreased expression of Anx D1 indicated decreased defensive response; the decreased expression of SHMT1 indicated decreased respiration; the decreased expression of COMT2 indicated decreased response of other funtions; the increased expression of NDPK indicated increased transcription and protein synthesis; the increased expression of PR1 and CHI1 indicated increased pathogen invasion; the increased expression of ORC5 and MPK5 indicated the reduced DNA replicating activity; the decreased expression of POLD1 indicated the reduced DNA repair activity. Our results provide new insights at the proteomic level into the Pb-induced responses, defensive responses and toxic effects, and provide new molecular markers of the early events of plant responses to Pb toxicity.
由于人为活动，环境中的离子铅（Pb）不断积累，对植物和植物消费者构成了潜在威胁。我们进行了这项研究，以揭示植物中 Pb 胁迫响应的分子机制。研究了 Pb（5.0 和 15.0μM）对葱蒜属鳞茎根端细胞有丝分裂、DNA 复制、基因表达和蛋白质的影响。结果表明，Pb 处理组根生长受到明显抑制。在不同浓度的 Pb 处理下观察到染色体畸变，有丝分裂指数降低。Pb 胁迫诱导洋葱根中活性氧（ROS）的积累。Pb 增加了 DNA 损伤并抑制了细胞周期进程。随着 Pb 浓度的增加和暴露时间的延长，上述毒性作用变得更加严重。在对照组和 Pb 暴露组之间共表达了 17 种差异蛋白。在 Pb 处理下，Anx D1 的表达减少表明防御反应减弱；SHMT1 的表达减少表明呼吸减弱；COMT2 的表达减少表明其他功能的反应减弱；NDPK 的表达增加表明转录和蛋白质合成增加；PR1 和 CHI1 的表达增加表明病原体入侵增加；ORC5 和 MPK5 的表达增加表明 DNA 复制活性降低；POLD1 的表达减少表明 DNA 修复活性降低。我们的研究结果在蛋白质组水平上为 Pb 诱导的响应、防御反应和毒性作用提供了新的见解，并为植物对 Pb 毒性早期反应的分子标记提供了新的线索。
