School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou, 215011, China.
Environmental Monitoring Station of Suzhou City, Suzhou, 215013, China.
Sci Rep. 2024 Sep 27;14(1):22315. doi: 10.1038/s41598-024-73771-4.
Lanthanum (La(III)) is recognized for its ability to mitigate heavy metal stress in plants. However, the inorganic La(III) salts and lanthanum oxide nanoparticles (LaO NPs) extensively used in agriculture are prone to soil immobilization, thereby compromising their bioavailability and posing environmental risks. This study synthesized and characterized the lanthanum(III)-amino acid chelate (La(III)-AA) from soybean protein isolate (SPI) hydrolysates. Maximum chelating rate (94.95%) was achieved under the conditions of mole ratio 1:1.5, pH 8.0, 50 ℃ and 5 h. Glu, Asp and Pro represent the primary La(III)-binding ligands. UV-vis and FTIR demonstrated that amino nitrogen and carboxyl oxygen participate in metal-ligand recognition. Scanning and Transmission electron microscopy showed that La(III) chelates with amino acids in a core-shell structure of uniform size. Consequently, a proposed chemical structure for the La(III)-AA complex was presented. A concentration of 20 mg/L La(III)-AA outperforms inorganic La salts in growth promotion and Cu detoxification. La(III)-AA significantly reduces the content of Cu (II) in rice tissues and enhances seedling tolerance to Cu (II) stress. This study provides a novel La(III)-based candidate for crop protection and furthers our understanding of rare earth element-induced mitigation of heavy metal stress.
镧（La(III)）因其能够减轻植物中的重金属压力而受到认可。然而，农业中广泛使用的无机镧（III）盐和氧化镧纳米粒子（LaO NPs）容易被土壤固定，从而降低其生物利用度并带来环境风险。本研究从大豆蛋白分离物（SPI）水解物中合成并表征了镧（III）-氨基酸螯合物（La(III)-AA）。在摩尔比为 1:1.5、pH 值为 8.0、50°C 和 5 h 的条件下，达到最大螯合率（94.95%）。Glu、Asp 和 Pro 是主要的 La(III)-结合配体。紫外-可见和傅里叶变换红外光谱表明，氨基氮和羧基氧参与金属-配体识别。扫描和透射电子显微镜显示，La(III)与氨基酸以均匀大小的核壳结构螯合。因此，提出了 La(III)-AA 配合物的化学结构。浓度为 20 mg/L 的 La(III)-AA 在促进生长和铜解毒方面优于无机镧盐。La(III)-AA 显著降低了水稻组织中 Cu(II)的含量，并增强了幼苗对 Cu(II)胁迫的耐受性。本研究为作物保护提供了一种新型的镧（III）候选物，并进一步加深了我们对稀土元素缓解重金属胁迫的理解。
