Polyamine Resistance Is Increased by Mutations in a Nitrate Transporter Gene NRT1.3 (AtNPF6.4) in Arabidopsis thaliana.
Polyamine Resistance Is Increased by Mutations in a Nitrate Transporter Gene NRT1.3 (AtNPF6.4) in Arabidopsis thaliana.
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DOI：
10.3389/fpls.2016.00834
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发表时间：
2016
影响因子：
5.6
通讯作者：
Takahashi T
中科院分区：
文献类型：
--
作者：
Tong W;Imai A;Tabata R;Shigenobu S;Yamaguchi K;Yamada M;Hasebe M;Sawa S;Motose H;Takahashi T
多胺是存在于所有生物体中的小的碱性化合物，并在各种生物过程中起作用。然而，与其他代谢途径相关的多胺传感、信号传导和响应机制在植物细胞中仍有待充分解决。作为一种方法，我们分离出拟南芥突变体，表现出增加的抗精胺的褪绿。我们在这里表明，两个突变体中有一个点突变的硝酸盐转运蛋白基因的NRT 1/PTR家族（NPF），NRT 1.3（AtNPF6.4）。这些突变体还表现出增加的腐胺和亚精胺的抗性，而NRT1.3的两个最接近的同源物，根特异性NRT1.1（AtNPF6.3）和叶柄特异性NRT1.4（AtNPF6.2）的功能丧失突变体，被证明具有正常的敏感性多胺。当GUS报告基因在NRT1.3启动子的控制下表达时，在叶肉细胞和茎皮层细胞中观察到GUS染色，但在表皮中没有，表明NRT1.3特异性地在薄壁组织中起作用。我们进一步发现，突变体幼苗的地上部分具有正常水平的多胺，但与野生型相比，去甲亚精胺的吸收减少。这些结果表明，多胺运输或代谢与硝酸盐运输的薄壁组织的拍摄。
Polyamines are small basic compounds present in all living organisms and act in a variety of biological processes. However, the mechanism of polyamine sensing, signaling and response in relation to other metabolic pathways remains to be fully addressed in plant cells. As one approach, we isolated Arabidopsis mutants that show increased resistance to spermine in terms of chlorosis. We show here that two of the mutants have a point mutation in a nitrate transporter gene of the NRT1/PTR family (NPF), NRT1.3 (AtNPF6.4). These mutants also exhibit increased resistance to putrescine and spermidine while loss-of-function mutants of the two closest homologs of NRT1.3, root-specific NRT1.1 (AtNPF6.3) and petiole-specific NRT1.4 (AtNPF6.2), were shown to have a normal sensitivity to polyamines. When the GUS reporter gene was expressed under the control of the NRT1.3 promoter, GUS staining was observed in leaf mesophyll cells and stem cortex cells but not in the epidermis, suggesting that NRT1.3 specifically functions in parenchymal tissues. We further found that the aerial part of the mutant seedling has normal levels of polyamines but shows reduced uptake of norspermidine compared with the wild type. These results suggest that polyamine transport or metabolism is associated with nitrate transport in the parenchymal tissue of the shoot.