Ma Yushen, Jie Hongdong, Tang Yanyi, Xing Hucheng, Jie Yucheng
College of Agronomy, Hunan Agricultural University, Changsha 410128, China.
Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Changsha 410128, China.
Plants (Basel). 2022 Jul 26;11(15):1941. doi: 10.3390/plants11151941.
Ramie cell walls play an important role in cadmium (Cd) detoxification. However, the Cd binding capacity of the cell wall components and the cell wall compositions among ramie species remains unclear. Therefore, this study compared two ramie populations ('Dazhuhuangbaima' (low-Cd-accumulating population) and 'Zhongzhu 1' (high-Cd-accumulating population)) with different Cd enrichment characteristics. The two ramie populations were treated with 0, 25, and 75 mg kg Cd for 30 days; then, their root length, plant height, biomass, Cd enrichment in the organs, subcellular Cd distribution, Cd content in the cell wall polysaccharides, and hemicellulose content were determined. The root length, plant height, biomass, and Cd enrichment in all organs were significantly higher ( ≤ 0.05) in 'Zhongzhu 1' than in 'Dazhuhuangbaima' under Cd stress. In addition, the subcellular Cd distribution analysis revealed that Cd was mainly found in the cell wall in both ramie populations. Among the cell wall fractions, Cd was mainly bound to the hemicelluloses, with 60.38-73.10% and 50.05-64.45% Cd accumulating in the 'Zhongzhu 1' and 'Dazhuhuangbaima' cell wall hemicelluloses, respectively. However, the Cd concentration in the 'Zhongzhu 1' hemicellulose was significantly higher ( ≤ 0.05) than that in the 'Dazhuhuangbaima' hemicellulose. Hemicellulose content analysis further revealed that the hemicellulose concentration increased with the Cd concentration in both populations, but it was significantly higher ( ≤ 0.05) in 'Zhongzhu 1' than in 'Dazhuhuangbaima' across all Cd treatments. Thus, ramie copes under Cd stress by increasing the hemicellulose content in the cell wall. The findings in this study confirm that hemicellulose is the main enrichment site for Cd in ramie. It also provides a theoretical basis for Cd enrichment breeding in ramie.
苎麻细胞壁在镉（Cd）解毒过程中发挥着重要作用。然而，苎麻品种间细胞壁成分的镉结合能力以及细胞壁组成仍不清楚。因此，本研究比较了两个具有不同镉富集特性的苎麻群体（“大苎黄白马”（低镉积累群体）和“中苎1号”（高镉积累群体））。对这两个苎麻群体分别用0、25和75 mg kg镉处理30天；然后，测定它们的根长、株高、生物量、各器官中的镉富集量、亚细胞镉分布、细胞壁多糖中的镉含量以及半纤维素含量。在镉胁迫下，“中苎1号”的根长、株高、生物量以及所有器官中的镉富集量均显著高于（≤0.05）“大苎黄白马”。此外，亚细胞镉分布分析表明，两个苎麻群体中的镉主要存在于细胞壁中。在细胞壁组分中，镉主要与半纤维素结合，“中苎1号”和“大苎黄白马”细胞壁半纤维素中积累的镉分别为60.38 - 73.10%和50.05 - 64.45%。然而，“中苎1号”半纤维素中的镉浓度显著高于（≤0.05）“大苎黄白马”半纤维素中的镉浓度。半纤维素含量分析进一步表明，两个群体中半纤维素浓度均随镉浓度升高而增加，但在所有镉处理水平下，“中苎1号”的半纤维素浓度均显著高于（≤0.05）“大苎黄白马”。因此，苎麻在镉胁迫下通过增加细胞壁中的半纤维素含量来应对。本研究结果证实，半纤维素是苎麻中镉的主要富集位点。这也为苎麻镉富集育种提供了理论依据。
