Preferential sorption of phenolic phytotoxins to soil: Implications for altering the availability of allelochemicals
Preferential sorption of phenolic phytotoxins to soil: Implications for altering the availability of allelochemicals
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DOI：
10.1021/jf053167q
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发表时间：
2006-04-19
影响因子：
6.1
通讯作者：
Xing, BS
中科院分区：
文献类型：
--
作者：
Tharayil, N;Bhowmik, PC;Xing, BS
化感作用是次生代谢物介导的植物间相互作用，在当前农业科学和入侵生态学中得到越来越多的应用。然而，对土壤的吸附作用在改变复杂化感化学混合物中组分的生物利用度方面的作用仍然不清楚。因此，在粉壤土中，利用具有代表性的植物酚酸混合物，即羟基苯甲酸、香豆酸、香豆酸和阿魏酸，研究了对土壤的优先吸收在改变植物渗出物化学成分中的作用。实验采用间歇平衡技术，数据拟合到Freundlich等温线。采用浓度依赖性吸附系数（K-d）在10 μ g mL（-1）下评估酚酸在不同体系中的吸附亲和力。随着固相溶解，所有的酚酸都表现出很强的位置特异性吸附，从它们的非线性等温线可以看出。有机物的去除大大降低了所有酚酸的吸附亲和力。即使在低浓度的酚酸下，也观察到对吸附位点的直接竞争。香豆酸的存在使羟基苯甲酸的K-d降低90%以上。在阿魏酸存在的情况下，约95%的吸附香草酸被置换到土壤溶液中。羟基苯甲酸对其他酚酸的吸附亲和力无明显影响，而阿魏酸对其他酚酸的吸附作用较小。位移模式表明-OH和-COOH基团对酚酸的定向吸附。土壤有机质具有优先吸附作用。本研究首次阐明了植物次生代谢物在土壤基质中的竞争吸收特性。结果表明，对土壤的优先吸收可以改变混合物中植物渗出液的有效性，从而可能介导其植物毒性作用。
Allelopathy, secondary metabolite-mediated plant-to-plant interaction, is gaining application in current agricultural science as well as in invasion ecology. However, the role of sorption to soil in modifying the bioavailability of components in complex allelochemical mixtures is still obscure. Hence, the role of preferential sorption to soil in altering the chemical composition of plant exudates was studied in a silt loam soil using representative mixtures of plant phenolic acids, namely, hydroxybenzoic acid, vanillic acid, coumaric acid, and ferulic acid. The experiment was conducted using a batch equilibration technique, and data were fitted to a Freundlich isotherm. The concentration-dependent sorption coefficient (K-d) at 10 mu g mL(-1) was used to assess the sorption affinity of phenolic acids across different systems. Along with solid phase dissolution, all of the phenolic acids exhibited strong site-specific sorption, as evident from their nonlinear isotherms. Removal of organic matter substantially decreased the sorption affinity of all phenolic acids. Direct competition for sorption sites was observed even at low concentrations of phenolic acids. The K-d of hydroxybenzoic acid was decreased more than 90% in the presence of coumaric acid. About 95% of sorbed vanillic acid was displaced into the soil solution in the presence of ferulic acid. Hydroxybenzoic acid did not affect the sorption affinity of other phenolic acids significantly, whereas ferulic acid showed low displacement by other phenolic acids. The displacement pattern indicated directional sorption of phenolic acids with -OH and -COOH groups. Soil organic matter was associated with preferential sorption. This is the first study to elucidate competitive sorption characteristics of plant secondary metabolites in soil matrix. The results demonstrate that preferential sorption to soil can alter the availability of plant exudates in mixtures and thus may mediate their phytotoxic effects.