The Arabidopsis dual-affinity nitrate transporter gene AtNRT1.1. (CHL1) is activated and functions in nascent organ development during vegetative and reproductive growth
The Arabidopsis dual-affinity nitrate transporter gene AtNRT1.1. (CHL1) is activated and functions in nascent organ development during vegetative and reproductive growth
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DOI：
10.1105/tpc.13.8.1761
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发表时间：
2001-08-01
期刊：
影响因子：
11.6
通讯作者：
Crawford, NM
中科院分区：
文献类型：
--
作者：
Guo, FQ;Wang, RC;Crawford, NM
AtNRT1.1 （CHL1）转运体为拟南芥的硝酸盐吸收提供了一个主要机制，并被认为定位于成熟根的表皮和皮层，硝酸盐的大部分吸收发生在那里。通过与GFP/GUS标记基因的融合，我们发现CHL1的表达集中在主根和侧根的尖端，在表皮和皮层的信号非常低。时间过程研究表明，CHL1在幼苗发育早期和侧根形成早期在主根尖被激活。在茎中也发现了强烈的CHL1表达，主要集中在嫩叶和发育中的花蕾中，而在茎的分生组织中则没有。这些表达模式被免疫定位证实，并引导我们研究CHL1在发育器官生长中的特异性功能。ch1突变体显示出新生根、茎、叶和花蕾的生长减少。在没有添加硝酸盐的情况下，突变体新生主根的生长受到抑制，而侧根原基的伸长在低硝酸盐和酸性ph下受到抑制。有趣的是，chl1突变体也表现出晚花表型。这些结果表明，在营养生长和生殖生长过程中，CHL1在芽和根的新生器官的生长中都被激活并发挥作用。
The AtNRT1.1 (CHL1) transporter provides a primary mechanism for nitrate uptake in Arabidopsis and is expected to localize to the epidermis and cortex of the mature root, where the bulk of nitrate uptake occurs. Using fusions to GFP/GUS marker genes, we found CHL1 expression concentrated in the tips of primary and lateral roots, with very low signals in the epidermis and cortex. A time-course study showed that CHL1 is activated in the primary root tip early in seedling development and at the earliest stages of lateral root formation. Strong CHL1 expression also was found in shoots, concentrated in young leaves and developing flower buds but not in the shoot meristem. These expression patterns were confirmed by immunolocalization and led us to examine CHL1 function specifically in the growth of developing organs. chl1 mutants showed a reduction in the growth of nascent roots, stems, leaves, and flower buds. The growth of nascent primary roots was inhibited in the mutants even in the absence of added nitrate, whereas elongation of lateral root primordia was inhibited specifically at low nitrate and acidic pH. Interestingly, chl1 mutants also displayed a late-flowering phenotype. These results indicate that CHL1 is activated and functions in the growth of nascent organs in both shoots and roots during vegetative and reproductive growth.