Aluminum effect on organic acid production and accumulation in sorghum
Aluminum effect on organic acid production and accumulation in sorghum
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DOI：
10.1081/pln-200049202
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发表时间：
2005-01-01
影响因子：
2.1
通讯作者：
Araújo, EF
中科院分区：
文献类型：
--
作者：
Gonçalves, JFD;Cambraia, J;Araújo, EF
在pH为4.0的Clark’s营养液中，对铝（Al）耐磨性不同的两种高粱（高粱双色）进行了7天的铝浓度处理。测定了根、叶和外源溶液中有机酸的浓度，以及与这些酸的生物合成和降解有关的酶的活性。根系和叶片中主要有机酸的含量随铝处理的增加而增加，耐铝品种的有机酸含量较高。在铝胁迫下，苹果酸和t-乌头酸含量最多，绝对变化最大，尤其是耐铝品种。铝还改变了本研究中与有机代谢有关的大多数酶的活性。Al对苹果酸代谢酶的影响最为显著的是根部的延胡索酸酶（EC 4.2.1.2）和苹果酸脱氢酶（EC 1.1.1.37），以及根部的反式乌头酸对柠檬酸脱氢酶（EC 4.2.1.4）的影响。铝诱导的这两种酶的变化似乎有利于耐m品种比铝敏感品种产生、积累和分泌这两种有机酸。有机酸，特别是苹果酸，可能在这些高粱品种对高水平铝的耐受性中起重要作用。我们的数据支持了高粱对铝的耐受性主要由内部解毒机制控制的假设，可能涉及有机酸代谢。
Seedlings of two cultivars of sorghum (Sorghum bicolor) differing in aluminum (Al) tolerance grown in a pH 4.0 Clark's nutrient solution were exposed to Al at concentrations of 0 and 185 mu M for 7 days. The organic acid concentrations in the roots and leaves and in the external solution were determined, as well as the activities of the enzymes related to the biosynthesis and degradation of these acids. Contents of the main organic acids found in the roots and leaves increased with plant exposure to Al and were always higher in the aluminum (Al)-tolerant cultivar. Malic and t-aconitic acids were the most abundant and showed the highest absolute changes in the presence of Al in both cultivars, especially the Al-tolerant cultivar. Aluminum also changed the activities of most of the enzymes related to organic metabolism studied here. The more important effects of Al on the enzymes of the malic-acid metabolism were found on the fumarase (EC 4.2.1.2) and malate dehydrogenase (EC 1.1.1.37) in the roots, in addition to the fumarase in the leaves and on the enzymes of the trans-aconitic acid on the citrate dehydratase (EC 4.2.1.4), especially in the roots. Aluminum-induced changes in these enzymes in the two sorghum cultivars seem to favor a higher production, accumulation, and exudation of these two organic acids in the M-tolerant cultivar compared with the Al-sensitive one. Organic acids, especially malic acid, probably play an important role in these sorghum cultivar's, tolerances to high levels of Al. Our data support the hypothesis that Al tolerance in sorghum is controlled mainly by an internal detoxification mechanism, probably involving organic acid metabolism.