Role of aluminum-binding ligands in aluminum resistance of Eucalyptus camaldulensis and Melaleuca cajuputi
Role of aluminum-binding ligands in aluminum resistance of Eucalyptus camaldulensis and Melaleuca cajuputi
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DOI：
10.1007/s11104-007-9464-5
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发表时间：
2008-01-01
期刊：
影响因子：
4.9
通讯作者：
Kojima, Katsumi
中科院分区：
文献类型：
--
作者：
Tahara, Ko;Norisada, Mariko;Kojima, Katsumi
我们研究了铝结合配体在两株抗铝桃金娘树根排铝和根内铝解毒中的作用及其作为抗铝机制的作用。和彩叶千层草。用0 mM和1 mM的AlCl3溶液处理这些植物的根，比较了它们与铝敏感种的根中分泌和根尖中的配位体的数量。在铝处理下，所有物种的根部分泌的众所周知的配体(柠檬酸、草酸和苹果酸)都很低。根分泌物在铝处理下的铝结合量较高，且高于毛白杨。凝胶过滤层析表明，只有赤杨根分泌一种低分子量铝结合配基。另一方面，铝处理下的根尖细胞汁液对铝的结合能力与抗性和敏感树种相似。这些结果表明，根部分泌未知的低分子铝结合配体对铝产生排斥作用，从而导致油茶对铝的抗性，而Cajuputi对铝的抗性机制不同于根部分泌配体或根尖内部配体的浓度。
We investigated the roles of Al-binding ligands in Al exclusion from roots and in internal Al detoxification in roots as Al resistance mechanisms in two Al-resistant Myrtaceae trees, Eucalyptus camaldulensis Dehnh. and Melaleuca cajuputi Powell. The amounts of ligands secreted from roots and contained in root tips of these species were compared with those of an Al-sensitive species, Melaleuca bracteata F. Muell., after the roots were exposed to 0 or 1 mM AlCl3 solution. Secretion of well-known ligands (citrate, oxalate, and malate) from roots under Al treatment was low in all species. However, in E. camaldulensis, the Al-binding capacity of root exudates under Al treatment was considerable and was higher than that in M. bracteata. Gel filtration chromatography revealed that a low-molecular-weight Al-binding ligand was secreted from roots in response to Al only in E. camaldulensis. On the other hand, the Al-binding capacity of cell sap in root tips under Al treatment was similar for the resistant and sensitive species. These results suggest that Al exclusion by secretion of the unknown low-molecular-weight Al-binding ligand from roots contributes to the Al resistance of E. camaldulensis, whereas M. cajuputi has developed Al-resistance mechanisms other than secretion of ligands from roots or concentration of internal ligands in root tips.