College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China.
Teaching Center, Zhejiang Open University, Hangzhou 310012, China.
Sci Total Environ. 2023 Sep 10;890:164184. doi: 10.1016/j.scitotenv.2023.164184. Epub 2023 May 22.
Nitrogen (N) fertilization can improve the phytoremediation of contaminated soils. However, limited information is available on the effects and mechanisms of N availability on Cadmium (Cd) phytoextraction by dioecious plants. This study employed female and male Populus cathayana to examine sex-specific long-distance transport and cell wall Cd sequestration. Females had a greater ability to transport Cd from roots to shoots and accumulated more Cd in leaves, but had less Cd bound to the cell wall and S-containing ligands than males, irrespective of N availability. N availability affected the sex-specific ability to transport Cd and chelate it within cell walls and with S-containing ligands. Low N promoted phloem-mediated upward and downward Cd transport and total Cd accumulation in both sexes, and such effects on phloem-mediated downward Cd transport were greater than those on upward Cd transport in males. However, low-N concentration-induced Cd phloem transport was more significant in females than males. In females, low N reduced Cd accumulation in leaves via increased phloem-mediated Cd downward transport, and this Cd was subsequently sequestered in the bark and root cell walls. In contrast, for males, high N promoted xylem-mediated Cd transport to shoots and Cd sequestration in the bark but reduced phloem-mediated Cd downward transport and subsequent sequestration in root cell walls. Sex-specific genes related to root Cd transport and translocation from roots to shoots were also affected by N supply in roots. These results suggested that N availability reduced the sex-based difference in total Cd accumulation, translocation and Cd detoxification, and males showed stronger Cd tolerance than females at both N availabilities.
氮（N）施肥可以改善污染土壤的植物修复。然而，关于 N 供应对雌雄异株植物镉（Cd）植物提取的影响和机制的信息有限。本研究采用雌性和雄性白杨来研究性别特异性的长距离运输和细胞壁 Cd 螯合。与 N 供应无关，雌性具有从根部向地上部运输 Cd 的更大能力，并在叶片中积累更多的 Cd，但与细胞壁和含 S 配体结合的 Cd 较少。N 供应影响性别特异性运输 Cd 和与细胞壁和含 S 配体螯合 Cd 的能力。低 N 促进韧皮部介导的 Cd 向上和向下运输以及两性的总 Cd 积累，并且这种对韧皮部介导的向下 Cd 运输的影响大于对雄性的向上 Cd 运输的影响。然而，低-N 浓度诱导的 Cd 韧皮部运输在雌性中比雄性更为显著。在雌性中，低 N 通过增加韧皮部介导的 Cd 向下运输减少叶片中的 Cd 积累，并且随后将 Cd 螯合到树皮和根细胞壁中。相比之下，对于雄性，高 N 促进木质部介导的 Cd 向地上部的运输和 Cd 在树皮中的螯合，但减少韧皮部介导的 Cd 向下运输以及随后在根细胞壁中的螯合。与根 Cd 运输和从根部向地上部转运有关的性别特异性基因也受到根系中 N 供应的影响。这些结果表明，N 供应降低了总 Cd 积累、转运和 Cd 解毒的性别差异，并且在两种 N 供应下雄性都比雌性表现出更强的 Cd 耐受性。
