Characterization of FRO1, a Pea Ferric-Chelate Reductase Involved in Root Iron Acquisition1
Characterization of FRO1, a Pea Ferric-Chelate Reductase Involved in Root Iron Acquisition1
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DOI：
10.1104/pp.010829
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发表时间：
2002-05
期刊：
影响因子：
7.4
通讯作者：
B. Waters;D. Blevins;D. Eide
中科院分区：
文献类型：
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作者：
B. Waters;D. Blevins;D. Eide
为了获取铁，许多植物通过嵌入根表皮细胞质膜中的铁（III）螯合还原酶将土壤中的铁（III）还原为铁（II）。还原产物随后被铁（II）转运蛋白吸收。这些活动是在缺铁条件下引起的。我们在这里描述了来自豌豆（Pisum sativum）的FRO1基因，该基因编码铁（III）螯合还原酶。与这一作用一致，FRO1与其他氧化还原酶蛋白相似，酵母中FRO1的表达增加了Fe（III）螯合还原酶的活性。此外，植物中FRO1 mRNA水平与铁（III）螯合还原酶活性相关。测定了fro1在根、叶和根瘤中的表达位点。FRO1 mRNA在整个根中检测到，但在外表皮细胞中含量最多。在叶片叶肉细胞中检测到表达。在根瘤中，侵染区和固氮区均检测到mRNA。这些结果表明，FRO1参与根对铁的吸收，并在铁在整个植物中的分布中发挥作用。FRO1的表征也为铁摄取的调控提供了新的见解。fro1的表达和还原酶活性仅在Sparkle缺铁的根中检测到，而这两个突变体在brzand dgl中都是组成部分，这两个突变体的铁积累调节不正确。相比之下，3个植物品系的茎部中FRO1的表达均响应铁的状态。这些结果表明，在brz和dgl突变体中，FRO1在根和芽中的调控存在差异，并且FRO1调控不正确，以响应茎源性铁状态信号。
To acquire iron, many plant species reduce soil Fe(III) to Fe(II) by Fe(III)-chelate reductases embedded in the plasma membrane of root epidermal cells. The reduced product is then taken up by Fe(II) transporter proteins. These activities are induced under Fe deficiency. We describe here the FRO1 gene from pea (Pisum sativum), which encodes an Fe(III)-chelate reductase. Consistent with this proposed role, FRO1 shows similarity to other oxidoreductase proteins, and expression of FRO1 in yeast conferred increased Fe(III)-chelate reductase activity. Furthermore,FRO1 mRNA levels in plants correlated with Fe(III)-chelate reductase activity. Sites of FRO1expression in roots, leaves, and nodules were determined.FRO1 mRNA was detected throughout the root, but was most abundant in the outer epidermal cells. Expression was detected in mesophyll cells in leaves. In root nodules, mRNA was detected in the infection zone and nitrogen-fixing region. These results indicate that FRO1 acts in root Fe uptake and they suggest a role in Fe distribution throughout the plant. Characterization of FRO1 has also provided new insights into the regulation of Fe uptake. FRO1expression and reductase activity was detected only in Fe-deficient roots of Sparkle, whereas both were constitutive in brzand dgl, two mutants with incorrectly regulated Fe accumulation. In contrast, FRO1 expression was responsive to Fe status in shoots of all three plant lines. These results indicate differential regulation of FRO1 in roots and shoots, and improper FRO1 regulation in response to a shoot-derived signal of iron status in the roots of thebrz and dgl mutants.