The Arabidopsis dual-affinity nitrate transporter gene AtNRT1.1 (CHL1) is regulated by auxin in both shoots and roots
The Arabidopsis dual-affinity nitrate transporter gene AtNRT1.1 (CHL1) is regulated by auxin in both shoots and roots
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DOI：
10.1093/jexbot/53.370.835
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发表时间：
2002-04-01
影响因子：
6.9
通讯作者：
Crawford, NM
中科院分区：
文献类型：
--
作者：
Guo, FQ;Wang, RC;Crawford, NM
拟南芥AtNRT1.1(CHL1)基因编码一个双亲和力硝酸盐转运体，参与低亲和力和高亲和力硝酸盐的摄取。定位研究表明，在拟南芥中，CHL1的表达主要针对新生器官以及根和茎的生长区域。在根中，CHL1的表达集中在初生根和侧根的顶端，并在侧根发生过程中被激活。在新梢中，CHL1在幼叶和发育中的花芽中有较强的表达。这些发现表明，CHL1的表达可能受生长信号的调节，如植物激素生长素。为了验证这一点，我们研究了CHL1的生长素调节。利用含有CHL1：：GUS/GFP DNA结构的转基因拟南芥植株，发现外源生长素处理或引入生长素过量产生突变(丝兰和根)会导致根和叶中CHL1：：GUS/GFP信号的强烈增加。当生长素处理成熟根诱导侧根形成时，CHL1：：GFP信号在柱花序细胞分裂和整个原基发育过程中显著增强。RNA印迹分析表明，在生长素处理30min内，整个幼苗的CHL1mRNA水平升高。拟南芥根和茎中CHL1的表达分布与生长素反应基因DR5：：GUS相似。这些结果表明，生长素是调节CHL1表达的重要信号，并有助于将CHL1的表达靶向到拟南芥的新生器官和根尖。
The AtNRT1.1 (CHL1) gene of Arabidopsis encodes a dual-affinity nitrate transporter and contributes to both low and high affinity nitrate uptake. Localization studies have shown that CHL1 expression is preferentially targeted to nascent organs and growing regions of roots and shoots in Arabidopsis. In roots, CHL1 expression is concentrated in the tips of primary and lateral roots and is activated during lateral root initiation. In shoots, strong CHL1 expression is found in young leaves and developing flower buds. These findings suggest that CHL1 expression might be regulated by a growth signal such as the phytohormone auxin. To test this, auxin regulation of CHL1 was examined. Using transgenic Arabidopsis plants containing CHL1::GUS/GFP DNA constructs, it was found that treatment with exogenous auxin or introduction of the auxin overproducing mutations (yucca and rooty) resulted in a strong increase in CHL1::GUS/GFP signals in roots and leaves. When mature roots were treated with auxin to induce lateral root formation, CHL1:: GFP signals were dramatically enhanced in dividing pericycle cells and throughout primordia development. RNA blot analysis showed that CHL1 mRNA levels in whole seedlings increase within 30 min of auxin treatment. The distribution of CHL1 expression in Arabidopsis roots and shoots was found to be similar to that of DR5:: GUS, a synthetic, auxin-responsive gene. These results indicate that auxin acts as an important signal regulating CHL1 expression and contributes to the targeting of CHL1 expression to nascent organs and root tips in Arabidopsis.