Concentrations of metals and potential metal-binding compounds and speciation of Cd, Zn and Cu in phloem and xylem saps from castor bean plants (Ricinus communis) treated with four levels of cadmium
Concentrations of metals and potential metal-binding compounds and speciation of Cd, Zn and Cu in phloem and xylem saps from castor bean plants (Ricinus communis) treated with four levels of cadmium
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DOI：
10.1111/ppl.12309
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发表时间：
2015-06-01
影响因子：
6.4
通讯作者：
Yoneyama, Tadakatsu
中科院分区：
文献类型：
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作者：
Hazama, Kenji;Nagata, Shinji;Yoneyama, Tadakatsu
研究了4周龄蓖麻（Ricinus communis）植物在0（对照）、0.1、1.0和10 M Cd处理3周后木质部和韧皮部汁液中金属（Cd、Zn、Cu、Fe和Mn）和潜在金属结合化合物[烟碱（NA）、硫醇化合物和柠檬酸盐]的浓度。0.1和1 M Cd处理对生长无明显损害，10 M Cd处理对生长有延缓作用。在0.1 M时，两个汁液中的镉浓度均高于培养液中的镉浓度，在1.0 M时相同，在10 M时较低，10 M时Cd降低了两个汁液中的Cu和Fe浓度。木质部液（20 M）中NA浓度高于Cu浓度，韧皮部液（150 M）中NA浓度高于Zn、Fe和Cu的总和。木质部和韧皮部的还原性谷胱甘肽浓度不同（分别为1-2 M和30-150 M），但氧化性谷胱甘肽浓度相似。韧皮部液中植物螯合素2的浓度从对照的0.8 M增加到10 M Cd处理下的8 M。游离柠檬酸在木质部液中为2 ~ 4 M，在韧皮部液中为70 ~ 100 M。1 M Cd处理植株韧皮部和木质部液中Cd的总结合形式分别为54%和8%。用proteinaseK处理韧皮部汁液减少了高分子化合物，同时增加了低分子cd -硫醇复合物的分数。电喷雾电离飞行时间质谱法在对照植株韧皮部液中鉴定出锌na、铁na和Cu-NA，木质部液中含有Cu-NA。
We examined the concentrations of metals (Cd, Zn, Cu, Fe and Mn) and potential metal-binding compounds [nicotianamine (NA), thiol compounds and citrate] in xylem and phloem saps from 4-week-old castor bean plants (Ricinus communis) treated with 0 (control), 0.1, 1.0, and 10 M Cd for 3 weeks. Treatment with 0.1 and 1 M Cd produced no visible damage, while 10 M Cd retarded growth. Cadmium concentrations in both saps were higher than those in the culture solution at 0.1 M, similar at 1.0 M and lower at 10 M. Cd at 10 M reduced Cu and Fe concentrations in both saps. NA concentrations measured by capillary electrophoresis-mass spectrometry (MS) in xylem sap (20 M) were higher than the Cu concentrations, and those in phloem sap (150 M) were higher than those of Zn, Fe and Cu combined. Reduced glutathione concentrations differed in xylem and phloem saps (1-2 and 30-150 M, respectively), but oxidized glutathione concentrations were similar. Phloem sap phytochelatin 2 concentration increased from 0.8 M in controls to 8 M in 10 M Cd. Free citrate was 2-4 M in xylem sap and 70-100 M in phloem sap. Total bound forms of Cd in phloem and xylem saps from 1 M Cd-treated plants were 54 and 8%, respectively. Treatment of phloem sap with proteinaseK reduced high-molecular compounds while increasing fractions of low-molecular Cd-thiol complexes. Zinc-NA, Fe-NA and Cu-NA were identified in the phloem sap fraction of control plants by electrospray ionization time-of-flight MS, and the xylem sap contained Cu-NA.