Internal detoxification mechanism of Al in hydrangea - Identification of Al form in the leaves

被引:246
作者
Ma, JF
Hiradate, S
Nomoto, K
Iwashita, T
Matsumoto, H
机构
[1] NATL INST AGROENVIRONM SCI, DIV PLANT ECOL, TSUKUBA, IBARAKI 305, JAPAN
[2] SUNTORY LTD, INST BIOORGAN RES, SHIMAMOTO, OSAKA 618, JAPAN
关键词
D O I
10.1104/pp.113.4.1033
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
An internal detoxification mechanism for Al was investigated in an Al-accumulating plant, hydrangea (Hydrangea macrophylla), focusing on Al forms present in the cells. The leaves of hydrangea contained as much as 15.7 mmol Al kg(-1) fresh weight, and more than two-thirds of the Al was found in the cell sap. Using Al-27-nuclear magnetic resonance, the dominant peak of Al was observed at a chemical shift of 11 to 12 parts per million in both intact leaves and the extracted cell sap, which is in good accordance with the chemical shift for the 1:1 Al-citrate complex. Purification of cell sap by molecular sieve chromatography (Sephadex G-10) combined with ion-exclusion chromatography indicated that Al in fractions with the same retention time as citric acid contributed to the observed Al-27 peak in the intact leaves. The molar ratio of Al to citric acid in the crude and purified cell sap approximated 1. The structure of the ligand chelated with Al was identified to be citric acid. Bioassay experiments showed that the purified Al complex from the cell sap did not inhibit root elongation of corn (Zea mays L.) and the viability of cells on the root tip surface was also not affected. These observations indicate that Al is bound to citric acid in the cells of hydrangea leaves.
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页码:1033 / 1039
页数:7
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