Chen Zanming, Zhao Xinyu, Zhang Shiyuan, Li Jianmin, Zhu Guopeng, Shi Liang, Chen Yahua
Sanya Institute of Nanjing Agricultural University, Sanya, 572024, China; College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Sanya Institute of Nanjing Agricultural University, Sanya, 572024, China; College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource, Nanjing Agricultural University, Nanjing, 210095, China.
Plant Physiol Biochem. 2025 Jul;224:109932. doi: 10.1016/j.plaphy.2025.109932. Epub 2025 Apr 16.
Cadmium (Cd) pollution in farmland soil poses serious threats to human health. The Cd transport and accumulation in the aboveground tissues of sweet potato (Ipomoea batatas L.) variety "Fu Cai 18″ and the characteristics of phloem-mediated Cd transport were elucidated in this study. Sweet potato seedlings grown in hydroponics were analyzed. The scanning through μ-XRF revealed that Cd was mainly distributed in cortex cells and vascular tissues of the stem; in leaves, it was mainly distributed in veins. The root regeneration and leaf smearing tests revealed that Cd accumulated in the stem can be redistributed to new growth sites and leaves; Cd accumulated in leaves can be transported to roots and young tissues through the phloem. Hence, Cd, transported to the aboveground tissues, can be re-transported in specific directions through the phloem. The leaf phloem exudate collection test demonstrated that the presence of Cd diminished calcium and zinc levels. Analysis of exudate via molecular sieve chromatography revealed that 50-70 % of Cd in the phloem of sweet potato may chelate with small-molecule compounds. Moreover, the contents of lysine, proline, and some carbohydrates (terpinetriose, lactose, stachyose, glucosamine, sorbitol, and maltose) significantly increased in the phloem exudate, suggesting that these substances participated in Cd transport in the phloem of sweet potatoes. These results highlight the critical function of phloem-mediated Cd transport, likely involving its chelation with small molecules and specific elements and metabolites. These results can potentially provide a theoretical basis for understanding the mechanism underlying heavy metal transport in sweet potato.
农田土壤中的镉（Cd）污染对人类健康构成严重威胁。本研究阐明了甘薯（Ipomoea batatas L.）品种“福菜18”地上组织中镉的转运和积累以及韧皮部介导的镉转运特性。对水培生长的甘薯幼苗进行了分析。通过μ-XRF扫描发现，镉主要分布在茎的皮层细胞和维管组织中；在叶片中，它主要分布在叶脉中。根再生和叶片涂抹试验表明，茎中积累的镉可以重新分配到新的生长部位和叶片中；叶片中积累的镉可以通过韧皮部运输到根和幼嫩组织中。因此，转运到地上组织的镉可以通过韧皮部在特定方向上重新运输。叶片韧皮部渗出液收集试验表明，镉的存在降低了钙和锌的含量。通过分子筛色谱对渗出液进行分析发现，甘薯韧皮部中50-70%的镉可能与小分子化合物螯合。此外, 韧皮部渗出液中赖氨酸、脯氨酸和一些碳水化合物（松三糖、乳糖、水苏糖、氨基葡萄糖、山梨醇和麦芽糖）的含量显著增加，表明这些物质参与了甘薯韧皮部中镉的运输。这些结果突出了韧皮部介导的镉运输的关键作用，可能涉及其与小分子、特定元素和代谢物的螯合。这些结果可能为理解甘薯中重金属运输的潜在机制提供理论依据。
