Differential Al resistance and citrate secretion in barley (Hordeum vulgare L.)
Differential Al resistance and citrate secretion in barley (Hordeum vulgare L.)
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DOI：
10.1007/s00425-003-1043-2
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发表时间：
2003-09-01
期刊：
影响因子：
4.3
通讯作者：
Takeda, K
中科院分区：
文献类型：
--
作者：
Zhao, ZQ;Ma, JF;Takeda, K
大麦（Hordeum vulgare L.）小杂粮作物中，对铝毒最敏感的品种是玉米，品种间的抗铝性存在差异。我们研究了21个大麦品种的差异铝抗性的机制。铝胁迫下，根系分泌柠檬酸。柠檬酸盐分泌与铝抗性呈正相关（Al根伸长）/（无铝根伸长）]和柠檬酸分泌与根尖铝含量呈负相关，这表明，柠檬酸从根尖分泌起着重要的作用，排除铝，从而解毒铝。铝诱导的柠檬酸分泌的特点是使用铝抗性品种（Sigurdkorn）和铝敏感品种（Kearney）。在Sigurdkorn，铝诱导的柠檬酸分泌发生在20分钟内，分泌并没有增加，随着外部铝浓度的增加。铝诱导的柠檬酸分泌在低温（6 ℃）下停止，并被阴离子通道抑制剂抑制。铝暴露在Sigurdkorn根尖内部柠檬酸盐含量增加，但在科尔尼没有受到影响。柠檬酸合成酶活性不受铝的抗铝和铝敏感品种。在小麦、黑麦和小黑麦中，大麦的有机酸阴离子分泌速率最低。
While barley (Hordeum vulgare L.) is the most sensitive species to Al toxicity among small-grain crops, variation in Al resistance between cultivars does exist. We examined the mechanism responsible for differential Al resistance in 21 barley varieties. Citrate was secreted from the roots in response to Al stress. A positive correlation between citrate secretion and Al resistance [(root elongation with Al)/(root elongation without Al)] and a negative correlation between citrate secretion and Al content of root apices, were obtained, suggesting that citrate secretion from the root apices plays an important role in excluding Al and thereby detoxifying Al. The Al-induced secretion of citrate was characterized using an Al-resistant variety (Sigurdkorn) and an Al-sensitive variety (Kearney). In Sigurdkorn, Al-induced secretion of citrate occurred within 20 min, and the secretion did not increase with increasing external Al concentration. The Al-induced citrate secretion ceased at low temperature (6 degreesC) and was inhibited by anion-channel inhibitors. Internal citrate content of root apices was increased by Al exposure in Sigurdkorn, but was not affected in Kearney. The activity of citrate synthase was unaffected by Al in both Al-resistant and Al-sensitive varieties. The secretion rate of organic acid anions from barley was the lowest among wheat, rye and triticale.