Relationship between molecular characteristics of soil humic fractions and glycolytic pathway and krebs cycle in maize seedlings
Relationship between molecular characteristics of soil humic fractions and glycolytic pathway and krebs cycle in maize seedlings
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DOI：
10.1016/j.soilbio.2007.07.006
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发表时间：
2007-12-01
影响因子：
9.7
通讯作者：
Piccolo, Alessandro
中科院分区：
文献类型：
--
作者：
Nardi, Serenella;Muscolo, Adele;Piccolo, Alessandro
用制备型高效体积排阻色谱法（HPSEC）将从火山土中分离出的腐殖酸（HA）分离成分子量递减的3个组分（I、II和III）。通过热解-GC-MS（用四甲基氢氧化铵热化学分解）和NMR光谱表征了大部分土壤HA及其粒度组分的分子含量。以玉米（Zea mays（L.）幼苗腐殖酸组分的元素分析和核磁共振谱表明，极性碳（主要是碳水化合物）的含量随着分离组分分子大小的减小而增加。通过在线热化学分解的产物显示，腐殖酸样品中具有最小刚性分子构象的最小尺寸级分（级分III）具有最低含量的木质素部分和最大量的其他非木质素芳香族化合物。散装HA和三个腐殖酸组分影响相关的酶活性的糖酵解和三羧酸循环（TCA）以不同的方式取决于分子大小，分子特征和浓度。四个组分促进代谢途径的总体效果顺序为：III > HA > II > I。馏分III，无论是单独或合并到散装HA的最大效果，是由于一个灵活的构象结构，促进了更有效的扩散，生物活性腐殖成分的玉米细胞。更好地了解土壤腐殖物质的分子结构与植物活性之间的关系，可能对增加植物固碳和将大气中的CO2重定向到生物燃料资源具有实际意义。(C)2007爱思唯尔有限公司保留所有权利。
A humic acid (HA) isolated from a volcanic soil was separated in three fractions of decreasing molecular size (I, II and III) by preparative high performance size exclusion chromatography (HPSEC). The molecular content of the bulk soil HA and its size fractions was characterized by pyrolysis-GC-MS (thermochemolysis with tetramethylammonium hydroxide) and NMR spectroscopy. All soil humic materials were used to evaluate their effects on the enzymatic activities involved in glycolytic and respiratory processes of Zea mays (L.) seedlings. The elementary analyses and NMR spectra of the humic fractions indicated that the content of polar carbons (mainly carbohydrates) increased with decreasing molecular size of separated fractions. The products evolved by on-line thermochemolysis showed that the smallest size fraction (Fraction III) with the least rigid molecular conformation among the humic samples had the lowest content of lignin moieties and the largest amount of other non-lignin aromatic compounds. The bulk HA and the three humic fractions affected the enzyme activities related to glycolysis and tricarboxylic acid cycle (TCA) in different ways depending on molecular size, molecular characteristics and concentrations. The overall effectiveness of the four fractions in promoting the metabolic pathways was in the order: III > HA > II > I. The largest effect of Fraction III, either alone or incorporated into the bulk HA, was attributed to a flexible conformational structure that promoted a more efficient diffusion of bioactive humic components to maize cells. A better knowledge of the relationship between molecular structure of soil humic matter and plant activity may be of practical interest in increasing carbon fixation in plants and redirect atmospheric CO2 into bio-fuel resources. (C) 2007 Elsevier Ltd. All rights reserved.