Effect of oxidizing power of roots on iodine uptake by rice plants
Effect of oxidizing power of roots on iodine uptake by rice plants
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DOI：
10.1111/j.1747-0765.2005.tb00018.x
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发表时间：
2005-02-01
影响因子：
2
通讯作者：
Yonebayashi, K
中科院分区：
文献类型：
--
作者：
Yamada, H;Takeda, C;Yonebayashi, K
虽然碘对植物有害，但水稻（Oryza sativa L.）比溴更有选择性地吸收碘。为了解释这种选择性吸收，作者基于以下事实提出了以下假设：（I-2 + 2 e = 2 I（-））的值低于（Br-2 + 2 e = 2Br（-））和（Fe ~（3 + +）e = Fe ~（2+）），水稻根系能将亚铁离子（Fe ~（2+））氧化为三价铁离子（Fe ~（3+）），即水稻植物通过其根部的氧化能力将碘离子（I-）氧化成分子碘（I-2），并且比碘离子更有选择性地吸收所形成的分子碘。相比之下，溴仅以离子（Br-）的形式被水稻吸收。根据这一假说，水稻根系的氧化能力与吸收碘量之间应存在显著的相关性。因此，在水培条件下，用8个水稻品种研究了根系氧化能力与吸收碘浓度之间的关系。水稻幼苗，发芽后14天，培养在溶液中含有1毫克L-1的碘离子和溴离子各为3天。基于根氧化1-萘胺的量来评价水稻根的氧化能力。氧化力与根系吸收碘浓度呈显著正相关（0.78，n = 16，0.1%显著水平）。然而，没有发现根的氧化能力和溴吸收量之间的关系。
Although iodine is harmful to plants, rice plants (Oryza sativa L.) absorbed iodine more selectively than bromine. To explain this selective absorption, the authors proposed the following hypothesis based on the fact that the standard redox potential for (I-2 + 2e = 2I(-)) is lower than that for (Br-2 + 2e = 2Br(-)) and (Fe3+ + e = Fe2+), and the roots of rice plants are able to oxidize ferrous ion (Fe2+) into ferric ion (Fe3+), namely rice plants oxidize iodide ion (I-) to form molecular iodine (I-2) via the oxidizing power of their roots, and absorb the molecular iodine formed more selectively than iodide ion. Bromine, by contrast, is absorbed by rice plants only in the form of ion (Br-). According to this hypothesis, there should be a significant correlation between the oxidizing power of the rice roots and the amount of iodine absorbed. Therefore, the relationship between the oxidizing power of the roots and the concentration of iodine absorbed was studied in a water culture using 8 varieties of rice plants. Rice seedlings, 14 d after germination, were cultured in a solution containing 1 mg L-1 each of iodide and bromide ions for 3 d. The oxidizing power of the rice roots was evaluated based on the amount of 1-naphthylamine oxidized by the roots. A significant correlation (0.78, n = 16, 0.1% significant level) was found between the oxidizing power and the concentration of iodine absorbed by the roots. However, no relationship was found between the oxidizing power of the roots and the amount of bromine absorbed.