Aluminum distribution and reactive oxygen species accumulation in root tips of two Melaleuca trees differing in aluminum resistance
Aluminum distribution and reactive oxygen species accumulation in root tips of two Melaleuca trees differing in aluminum resistance
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DOI：
10.1007/s11104-008-9593-5
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发表时间：
2008-06-01
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;Yamanoshita, Takashi;Kojima, Katsumi
为了阐明桃金娘科树种白千层（Melaleuca cajuputi Powell）高铝抗性的机制，研究了白千层根尖对铝的反应，并与铝敏感树种大苞白千层（M bracteata F.穆勒两个物种的幼苗的根用含有0或1 mM AlCl 3的钙溶液（pH 4.0）处理。铝处理3 h后，抑制根的伸长和胼胝质和木质素在根尖的沉积，这是铝伤害的典型标志，在M bracteata中诱导，但在M cajuputi中不诱导，但两种植物根尖中铝的积累相似。这些结果表明，内部耐铝机制，而不是铝排斥机制，是负责的铝抗性M。cajuputi。铝处理3 h后，与根尖紧密结合的铝量，用解吸液洗涤后剩余的铝，在M cajuputi比M bracteata少。在M bracteata，6小时的铝处理引发的积累过氧化氢（H2O2）在根尖尽管上调的抗氧化机制，过氧化物酶的活性和还原型谷胱甘肽的浓度。铝处理6 h对木麻黄根尖H2O2浓度无明显影响，但降低了过氧化物酶活性，提高了还原型谷胱甘肽浓度。这些结果表明，铝紧密结合到根尖参与抑制H2O2的积累和内部铝耐度在M cajuputi，和H2O2的积累或细胞环境的变化，带来H2O2积累，尽管上调抗氧化机制导致铝诱导抑制根伸长。
To elucidate the mechanism of the high aluminum (Al) resistance of a Myrtaceae tree, Melaleuca cajuputi Powell, we investigated the responses of root tips to Al and compared them with those of an Al-sensitive species, M bracteata F. Muell. Roots of seedlings of both species were treated with a calcium solution (pH 4.0) containing 0 or 1 mM AlCl3. After 3 h of Al treatment, inhibition of root elongation and deposition of callose and lignin in root tips, typical signs of Al injury, were induced in M bracteata but not in M cajuputi, yet Al accumulation in root tips was similar in both species. These results indicate that internal Al tolerance mechanisms, not Al exclusion mechanisms, are responsible for the Al resistance of M. cajuputi. After 3 h of Al treatment, amount of Al tightly bound to root tips, Al remaining after washing with a desorbing solution, was less in M cajuputi than in M bracteata. In M bracteata, 6 h of Al treatment triggered the accumulation of hydrogen peroxide (H2O2) in root tips despite the upregulation of antioxidant mechanisms, activity of peroxidase and concentration of reduced glutathione. In M cajuptiti, 6 h of Al treatment did not affect the concentration of H2O2, but decreased activity of peroxidase, and increased concentration of reduced glutathione in root tips. These results suggest that the less Al tightly bound to root tips is involved in the suppressing the H2O2 accumulation and the internal Al tolerance in M cajuputi, and that the H2O2 accumulation or changes in cellular environment that bring about H2O2 accumulation despite the upregulation of antioxidant mechanisms results in Al-induced inhibition of root elongation in M bracteata.