In vivo evidence that Ids3 from Hordeum vulgare encodes a dioxygenase that converts 2′-deoxymugineic acid to mugineic acid in transgenic rice
In vivo evidence that Ids3 from Hordeum vulgare encodes a dioxygenase that converts 2′-deoxymugineic acid to mugineic acid in transgenic rice
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DOI：
10.1007/s004250000453
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发表时间：
2001-04-01
期刊：
影响因子：
4.3
通讯作者：
Mori, S
中科院分区：
文献类型：
--
作者：
Kobayashi, T;Nakanishi, H;Mori, S
我们提出了大麦缺铁诱导基因Ids 3（Iron deficiency Specific clone no.3）。根编码双加氧酶，其催化从2 ′-脱氧麦根酸（DMA）到麦根酸（MA）的羟基化步骤。为了证明这一假设，我们将Ids 3基因导入水稻（Orvza sativa L.），其缺乏Ids 3同源物并分泌DMA，但不分泌MA。利用农杆菌介导的转化获得了携带Ids 3 cDNA或含有Ids 3的大麦基因组DNA片段（20 kb）的转基因水稻植株。在花椰菜花叶病毒35 S启动子控制下的Ids 3 cDNA在转基因水稻的根和叶中组成型表达，而与铁营养状态无关。与此相反，在携带大麦基因组片段的转化体的根中，响应于铁缺乏，Ids的转录物显着增加。在缺铁植株的叶片中也观察到Ids 3的轻微表达。蛋白质印迹分析证实了诱导的Ids 3在响应于Fe缺乏在携带基因组片段的转化体的根。这些表达模式表明Ids 3的5 '侧翼区在水稻中以及在大麦中作为强的Fz缺陷诱导型启动子起作用。在缺铁条件下，两种转基因水稻除了分泌DMA外，还分泌MA，而野生型水稻只分泌DMA。这是IDS 3是将DMA转化为MA的“MA合酶”的体内证据。
We proposed that an Fe-deficiency-induced gene, Ids3 (Iron deficiency Specific clone no. 3), from barley (Hordeum vulgare L.) roots encodes a dioxygenase that catalyzes the hydroxylation step from 2 ' -deoxymugineic acid (DMA) to mugineic acid (MA). To prove this hypothesis, we introduced the Ids3 gene into rice (Orvza sativa L.), which lacks Ids3 homologues and secretes DMA, but not MA. Transgenic rice plants, carrying either Ids3 cDNA or a barley genomic DNA fragment (20 kb) containing Ids3, were obtained using Agrobacterium-mediated transformation. Ids3 cDNA under the control of the cauliflower mosaic virus 35S promoter was constitutively expressed in both the roots and the leaves of the transgenic rice, regardless of Fe nutrition status. In contrast, in the roots of transformants carrying a barley genomic fragment, transcripts of Ids were markedly increased in response to Fe deficiency. Slight expression of Ids3 was also observed in the leaves of the Fe-deficient plants. Western blot analysis confirmed the induction of Ids3 in response to Fe deficiency in the roots of the transformants carrying a genomic fragment. These expression patterns indicate that the 5 ' -flanking region of Ids3 works as a strong Fz-deficiency-inducible promoter in rice, as well as in barley. Both kinds of transgenic rice secreted MA in addition to DMA under Fe-deficient conditions, but wild-type rice secreted only DMA. This is in vivo evidence that IDS3 is the "MA synthase" that converts DMA to MA.