Rahnamaei Yahyaabadi Narges, Zoufan Parzhak, Nasernakhaei Fatemeh
Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Department of Plant Production Engineering and Genetics, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Biometals. 2025 May 7. doi: 10.1007/s10534-025-00691-9.
Plants use various mechanisms to cope with cadmium (Cd) stress. Melatonin's impact on the root response to Cd stress, which is the first organ to detect its presence, has been less studied. This study aims to investigate the effects of melatonin pretreatment on the root strategies of Malva parviflora in response to Cd stress, focusing on the mechanisms of heavy metal tolerance. The plants, 42 days post-germination, were subjected to a 48-h pretreatment with 50 μM melatonin in a complete nutrient solution under controlled growth conditions. Following pretreatment, plants were exposed to a nutrient solution containing 50 μM Cd for 8 days. Comparative analyses were conducted on root length, weight, anatomical features, Cd content, Cd subcellular distribution, nutrient absorption, glutathione, and lignin. Melatonin pretreatment significantly enhanced root length and weight under Cd stress. It also increased the xylem and phloem area in the roots and promoted the absorption and translocation of essential nutrients such as Fe, Zn, Ca, and Mg to the shoots. Additionally, there was a marked increase in glutathione content and Cd proportion in the cell wall and organelle fractions in melatonin-pretreated roots. Notably, melatonin reduced overall plant Cd content and its translocation from roots to shoots, while decreasing root lignin content. This study demonstrates that melatonin plays an important role in managing Cd toxicity by improving morphological, anatomical, and biochemical characteristics of roots under Cd stress. The findings suggest that melatonin pretreatment can effectively alter Cd subcellular distribution, thereby mitigating its harmful effects in plants.
植物利用多种机制来应对镉（Cd）胁迫。褪黑素对根系对镉胁迫的反应的影响研究较少，而根系是检测镉存在的首个器官。本研究旨在探讨褪黑素预处理对小花锦葵根系应对镉胁迫策略的影响，重点关注重金属耐受机制。在可控生长条件下，将发芽42天的植株在完全营养液中用50μM褪黑素进行48小时预处理。预处理后，将植株暴露于含有50μM镉的营养液中8天。对根长、根重、解剖特征、镉含量、镉亚细胞分布、养分吸收、谷胱甘肽和木质素进行了比较分析。褪黑素预处理显著提高了镉胁迫下的根长和根重。它还增加了根中木质部和韧皮部的面积，并促进了铁、锌、钙和镁等必需养分向地上部的吸收和转运。此外，褪黑素预处理的根中，细胞壁和细胞器部分的谷胱甘肽含量和镉比例显著增加。值得注意的是，褪黑素降低了植株整体的镉含量及其从根到地上部的转运，同时降低了根中木质素的含量。本研究表明，褪黑素通过改善镉胁迫下根系的形态、解剖和生化特征，在应对镉毒性方面发挥着重要作用。研究结果表明，褪黑素预处理可以有效改变镉的亚细胞分布，从而减轻其对植物的有害影响。
