CYP707A3, a major ABA 8′-hydroxylase involved in dehydration and rehydration response in Arabidopsis thaliana
CYP707A3, a major ABA 8′-hydroxylase involved in dehydration and rehydration response in Arabidopsis thaliana
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DOI：
10.1111/j.1365-313x.2006.02683.x
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发表时间：
2006-04-01
期刊：
影响因子：
7.2
通讯作者：
Shinozaki, K
中科院分区：
文献类型：
--
作者：
Umezawa, T;Okamoto, M;Shinozaki, K
脱落酸 (ABA) 分解代谢是内源 ABA 水平的决定因素之一，影响植物生长和非生物胁迫反应的许多方面。主要的 ABA 分解代谢途径是由细胞色素 P450 CYP707A 家族催化的 ABA 8'-羟基化触发的。在拟南芥 CYP707A 的四个成员中，CYP707A3 的表达响应脱水和随后的再水化而被高度诱导。 T-DNA 插入 cyp707a3-1 突变体在膨大植物中含有较高的 ABA 水平，在幼苗生长早期表现出蒸腾速率降低和对外源 ABA 过敏。在脱水时，cyp707a3-1突变体比野生型积累了更高量的胁迫诱导的ABA，这一事件发生得相对较晚，并且与CYP707A3的缓慢干旱诱导一致。 cyp707a3 突变体植物表现出 ABA 诱导基因的过度表达和增强的耐旱性。相反，CYP707A3 的组成型表达缓解了 ABA 造成的生长迟缓，增加了蒸腾作用，并减少了肿胀和脱水植物中内源 ABA 的减少。综上所述，我们的结果表明 CYP707A3 在确定脱水期间和补液后 ABA 阈值水平方面发挥着重要作用。
Abscisic acid (ABA) catabolism is one of the determinants of endogenous ABA levels affecting numerous aspects of plant growth and abiotic stress responses. The major ABA catabolic pathway is triggered by ABA 8'-hydroxylation catalysed by the cytochrome P450 CYP707A family. Among four members of Arabidopsis CYP707As, the expression of CYP707A3 was most highly induced in response to both dehydration and subsequent rehydration. A T-DNA insertional cyp707a3-1 mutant contained higher ABA levels in turgid plants, which showed a reduced transpiration rate and hypersensitivity to exogenous ABA during early seedling growth. On dehydration, the cyp707a3-1 mutant accumulated a higher amount of stress-induced ABA than the wild type, an event that occurred relatively later and was coincident with slow drought induction of CYP707A3. The cyp707a3 mutant plants exhibited both exaggerated ABA-inducible gene expression and enhanced drought tolerance. Conversely, constitutive expression of CYP707A3 relieved growth retardation by ABA, increased transpiration, and a reduction of endogenous ABA in both turgid and dehydrated plants. Taken together, our results indicate that CYP707A3 plays an important role in determining threshold levels of ABA during dehydration and after rehydration.