A plant growth retardant, uniconazole, is a potent inhibitor of ABA catabolism in Arabidopsis
A plant growth retardant, uniconazole, is a potent inhibitor of ABA catabolism in Arabidopsis
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DOI：
10.1271/bbb.60077
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发表时间：
2006-07-01
影响因子：
1.6
通讯作者：
Mizutani, Masaharu
中科院分区：
文献类型：
--
作者：
Saito, Shigeki;Okamoto, Masanori;Mizutani, Masaharu
植物生长延缓剂（PGRs）通过抑制赤霉素的生物合成来抑制植物的新梢生长。在这项研究中，我们进行了详细的分析PGR对拟南芥脱落酸（阿坝）8-羟化酶，一个主要的阿坝分解代谢酶，最近被确定为CYP 707 As的抑制作用。在昆虫细胞中表达的CYP 707 A3微粒体的体外试验中，烯效唑-P比多效唑或四环素更有效地抑制CYP 707 A3活性，而测试的其他PGR没有显著抑制。烯效唑-P是阿坝8 ′-羟化酶的强竞争性抑制剂（Ki = 8.0nm）。烯效唑-P处理的拟南芥植物表现出增强的耐旱性。在烯效唑-P处理的植株中，内源阿坝水平比对照增加2倍，并且同时施用GA（4）没有抑制这种效应，表明这种效应不是由于赤霉素缺乏引起的。因此，烯效唑-P有效地抑制阿坝catalysts在拟南芥植物。并对唑类化合物抑制阿坝8 ′-羟化酶活性的构效关系进行了讨论。
Plant growth retardants (PGRs) reduce the shoot growth of plants by inhibiting gibberellin biosynthesis. In this study, we performed detailed analyses of the inhibitory effects of PGRs on Arabidopsis abscisic acid (ABA) 8-hydroxylase, a major ABA catabolic enzyme, recently identified as CYP707As. In an in vitro assay with CYP707A3 microsomes expressed in insect cells, uniconazole-P inhibited CYP707A3 activity more effectively than paclobutrazol or tetcyclacis, whereas the other PGRs tested did not inhibit it significantly. Uniconazole-P was found to be a strong competitive inhibitor (K-i = 8.0 nm) of ABA 8'-hydroxylase. Uniconazole-P-treated Arabidopsis plants showed enhanced drought tolerance. In uniconazole-P-treated plants, endogenous ABA levels increased 2-fold as compared with the control, and co-application of GA(4) did not suppress the effects, indicating that the effects were not due to gibberellin deficiency. Thus uniconazole-P effectively inhibits ABA catabolism in Arabidopsis plants. We also discuss the structure-activity relationship of the azole-type compounds on ABA 8'-hydroxylase inhibitory activity.