CYP707A1 and CYP707A2, which encode abscisic acid 8′-hydroxylases, are indispensable for proper control of seed dormancy and germination in Arabidopsis
CYP707A1 and CYP707A2, which encode abscisic acid 8′-hydroxylases, are indispensable for proper control of seed dormancy and germination in Arabidopsis
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DOI：
10.1104/pp.106.079475
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发表时间：
2006-05-01
期刊：
影响因子：
7.4
通讯作者：
Nambara, E
中科院分区：
文献类型：
--
作者：
Okamoto, M;Kuwahara, A;Nambara, E
内源脱落酸（阿坝）水平受激素的生物合成和催化作用的调节。阿坝8 '-羟化酶被认为是许多生理过程中的关键分解代谢酶。我们先前已经鉴定了拟南芥（Arabidopsis thaliana）CYP 707 A基因家族的四个成员（CYP 707 A1至CYP 707 A4）编码阿坝8 '-羟化酶，并且cyp 707 a2突变体在干燥和吸胀的种子中表现出阿坝水平的增加。在这项研究中，我们表明，cyp 707 a1突变体积累阿坝在干种子比cyp 707 a2突变体更高的水平。表达分析表明，CYP 707 A1主要在成熟中期表达，在成熟后期下调。同时，CYP 707 A2转录水平从成熟后期到成熟干种子增加。单突变体和双突变体cyp 707 a的表型分析表明，CYP 707 A1是重要的降低阿坝水平在成熟中期。另一方面，CYP 707 A2负责从晚成熟到萌发的阿坝水平的调节。此外，CYP 707 A1和CYP 707 A3也被证明参与萌发后的生长。空间表达分析表明，CYP 707 A1主要在中熟期的胚中表达，而CYP 707 A2在中熟至萌发期的胚和胚乳中均有表达。我们的研究结果表明，每个CYP 707 A基因在种子发育和萌发后生长过程中发挥着独特的作用。
Endogenous abscisic acid (ABA) levels are regulated by both biosynthesis and catabolism of the hormone. ABA 8'-hydroxylase is considered to be the key catabolic enzyme in many physiological processes. We have previously identified that four members of the Arabidopsis ( Arabidopsis thaliana) CYP707A gene family (CYP707A1 to CYP707A4) encode ABA 8'-hydroxylases, and that the cyp707a2 mutants showed an increase in ABA levels in dry and imbibed seeds. In this study, we showed that the cyp707a1 mutant accumulated ABA to higher levels in dry seeds than the cyp707a2 mutant. Expression analysis showed that the CYP707A1 was expressed predominantly during mid-maturation and was down-regulated during late-maturation. Concomitantly, the CYP707A2 transcript levels increased from late-maturation to mature dry seed. Phenotypic analysis of single and double cyp707a mutants indicates that the CYP707A1 is important for reducing ABA levels during mid-maturation. On the other hand, CYP707A2 is responsible for the regulation of ABA levels from late-maturation to germination. Moreover, CYP707A1 and CYP707A3 were also shown to be involved in postgermination growth. Spatial expression analysis suggests that CYP707A1 was expressed predominantly in embryo during mid-maturation, whereas CYP707A2 expression was detected in both embryo and endosperm from late-maturation to germination. Our results demonstrate that each CYP707A gene plays a distinct role during seed development and postgermination growth.