The Arabidopsis cytochrome P450CYP707A encodes ABA 8′-hydroxylases:: key enzymes in ABA catabolism
The Arabidopsis cytochrome P450CYP707A encodes ABA 8′-hydroxylases:: key enzymes in ABA catabolism
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DOI：
10.1038/sj.emboj.7600121
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发表时间：
2004-04-07
期刊：
影响因子：
11.4
通讯作者：
Nambara, E
中科院分区：
文献类型：
--
作者：
Kushiro, T;Okamoto, M;Nambara, E
植物中脱落酸（ABA）的激素作用是由其生物合成和分解代谢之间的精确平衡控制的。在植物中，ABA 8′-羟基化被认为在ABA分解代谢中起主导作用。ABA 8′-羟化酶为细胞色素P450 (P450)；然而，其对应的基因尚未被鉴定出来。通过系统发育和DNA芯片分析，从272个拟南芥P450基因中筛选出该酶的候选基因。这些候选基因在酵母中功能表达，揭示了CYP707A家族成员CYP707A1-CYP707A4编码ABA 8′-羟化酶。表达分析表明，CYP707A2与种子吸胀过程中ABA水平的快速下降有关。在干旱胁迫条件下，所有CYP707A基因均上调，补液后CYP707A基因水平显著升高。与表达分析一致，cyp707a2突变体在种子中表现出高休眠，积累的ABA含量比野生型高6倍。这些结果表明，CYP707A家族基因在控制植物ABA水平中起着重要的调控作用。
The hormonal action of abscisic acid (ABA) in plants is controlled by the precise balance between its biosynthesis and catabolism. In plants, ABA 8'-hydroxylation is thought to play a predominant role in ABA catabolism. ABA 8'-hydroxylase was shown to be a cytochrome P450 (P450); however, its corresponding gene had not been identified. Through phylogenetic and DNA microarray analyses during seed imbibition, the candidate genes for this enzyme were narrowed down from 272 Arabidopsis P450 genes. These candidate genes were functionally expressed in yeast to reveal that members of the CYP707A family, CYP707A1-CYP707A4, encode ABA 8'-hydroxylases. Expression analyses revealed that CYP707A2 is responsible for the rapid decrease in ABA level during seed imbibition. During drought stress conditions, all CYP707A genes were upregulated, and upon rehydration a significant increase in mRNA level was observed. Consistent with the expression analyses, cyp707a2 mutants exhibited hyperdormancy in seeds and accumulated six-fold greater ABA content than wild type. These results demonstrate that CYP707A family genes play a major regulatory role in controlling the level of ABA in plants.