Mechanism of the Removal of Aluminum Toxicity for Plant by Chemically Modified Lignins

化学改性木质素去除植物铝毒的机理

• 批准号: 12460074
• 负责人: MESHITSUKA Gyosuke
• 金额: $ 8万
• 依托单位: THE UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12460074/
• 关键词: Lignin; Soil conditioning agent; Aluminum ions; Forest; Acid soil; Alkaline oxygen oxidation; Complex formation; Root

Toxic effect of aluminum ions to plants is generally observed in the area of acidic soil, and is particularly serious if the sound surface soil is lost in which humic substances have important functions to remove those toxic effect. The authors have found that chemically modified lignins by radical sulfonation and alkaline-oxygen oxidation have the functions similar to the humic substances. The aims of this research were to find out the mechanisms why the chemically modified lignins had those positive effect.It was found that at least four different types of acid groups were introduced into the modified lignins, namely strong acid group, weak acid groups I - III. Strong acid group should be sulfonic acid group introduced by radical sulfonation reaction. Weak acid group I seems to be the aromatic carboxylic acid, and catecholic and muconic acid structures are included in weak acid group II. By the addition of aluminum, amount of acid groups, particularly weak acid group I was found to increase indicating the release of acidic proton by the formation of aluminum-lignin complex, which was also confirmed by ^<27>AL-NMR.

铝离子对植物的毒性作用在酸性土壤中普遍存在，在土壤表层失去良好土壤的情况下，铝离子对植物的毒性作用尤为严重，而土壤表层腐殖质对铝离子的毒性作用具有重要的消除作用。通过自由基磺化和碱氧氧化对木质素进行化学修饰，发现木质素具有类似腐殖质的功能。本研究的目的是找出化学修饰木质素具有这些积极作用的机制。结果表明，改性木质素中至少引入了四种不同类型的酸基，即强酸基、弱酸基I - III。强酸基应为自由基磺化反应引入的磺酸基。弱酸基团I似乎是芳香羧酸，而弱酸基团II包含儿茶酚和黏液酸结构。通过铝的加入，发现酸基团，特别是弱酸基团I的数量增加，表明酸性质子通过铝-木质素络合物的形成而释放，这也被^<27>AL-NMR证实。