College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China; Institute of Botany, Jiangsu Province and Chinese Academy Sciences, Nanjing, 210014, China.
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
Environ Pollut. 2021 Sep 1;284:117204. doi: 10.1016/j.envpol.2021.117204. Epub 2021 Apr 21.
Polycyclic aromatic hydrocarbons (PAHs), ubiquitous organic pollutants in the environment, can accumulate in humans via the food chain and then harm human health. MiRNAs (microRNAs), a kind of non-coding small RNAs with a length of 18-30 nucleotides, regulate plant growth and development and respond to environmental stress. In this study, it is demonstrated that miR164 can regulate root growth and adventitious root generation of wheat under phenanthrene exposure by targeting NAC (NAM/ATAF/CUC) transcription factor. We observed that phenanthrene treatment accelerated the senescence and death of wheat roots, and stimulated the occurrence of new roots. However, it is difficult to compensate for the loss caused by old root senescence and death, due to the slower growth of new roots under phenanthrene exposure. Phenanthrene accumulation in wheat roots caused to generate a lot of reactive oxygen species, and enhanced lipoxygenase activity and malonaldehyde concentration, meaning that lipid peroxidation is the main reason for root damage. MiR164 was up-regulated by phenanthrene, enhancing the silence of NAC1, weakening the association with auxin signal, and inhibiting the occurrence of adventitious roots. Phenanthrene also affected the expression of CDK (the coding gene of cyclin-dependent kinase) and CDC2 (a gene regulating cell division cycle), the key genes in the cell cycle of pericycle cells, thereby affecting the occurrence and growth of lateral roots. In addition, NAM (a gene regulating no apical meristem) and NAC23 may also be related to the root growth and development in wheat exposed to phenanthrene. These results provide not only theoretical basis for understanding the molecular mechanism of crop response to PAHs accumulation, but also knowledge support for improving phytoremediation of soil or water contaminated by PAHs.
多环芳烃（PAHs）是环境中普遍存在的有机污染物，可通过食物链在人体内积累，从而危害人类健康。miRNAs（microRNAs）是一种长度为 18-30 个核苷酸的非编码小分子 RNA，可调节植物的生长和发育，并对环境胁迫做出响应。在这项研究中，证明了 miR164 可以通过靶向 NAC（NAM/ATAF/CUC）转录因子来调节苯并[a]芘暴露下小麦的根生长和不定根生成。我们观察到，苯并[a]芘处理加速了小麦根的衰老和死亡，并刺激了新根的发生。然而，由于在苯并[a]芘暴露下新根的生长较慢，因此很难弥补老根衰老和死亡造成的损失。苯并[a]芘在小麦根中的积累导致产生了大量的活性氧，增强了脂氧合酶活性和丙二醛浓度，这意味着脂质过氧化是根损伤的主要原因。miR164 被苯并[a]芘上调，增强了 NAC1 的沉默作用，减弱了与生长素信号的关联，从而抑制了不定根的发生。苯并[a]芘还影响了细胞周期蛋白依赖性激酶（CDK）的编码基因 cyclin-dependent kinase（CDK）和细胞分裂周期（CDC2）的表达，这是中柱细胞细胞周期的关键基因，从而影响侧根的发生和生长。此外，NAM（调节无顶芽）和 NAC23 基因也可能与苯并[a]芘暴露下小麦的根生长和发育有关。这些结果不仅为理解作物对 PAHs 积累的响应的分子机制提供了理论依据，也为提高植物修复受 PAHs 污染的土壤或水的能力提供了知识支持。
