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.010126
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发表时间：
2001-08
期刊：
影响因子：
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通讯作者：
Fang-Qing Guo;Rongchen Wang;Mingsheng Chen;N. Crawford
中科院分区：
文献类型：
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作者：
Fang-Qing Guo;Rongchen Wang;Mingsheng Chen;N. Crawford
AtNRT1.1（CHL1）转运蛋白提供了一个主要的机制，在拟南芥中的硝酸盐吸收，并预计本地化的表皮和皮层的成熟根，在那里发生的大量的硝酸盐吸收。使用融合GFP/GUS标记基因，我们发现CHL1的表达集中在初级和侧根的尖端，在表皮和皮层的信号非常低。一个时间进程的研究表明，CHL1被激活的初级根尖在幼苗发育的早期和侧根形成的最早阶段。强CHL1表达也被发现在芽，集中在幼叶和发育中的花芽，但不是在地上部分生组织。这些表达模式通过免疫定位得到证实，并使我们能够检查CHL1在发育器官生长中的特异性功能。chl 1突变体显示新生根、茎、叶和花蕾的生长减少。即使在没有添加硝酸盐的情况下，在突变体中的新生初生根的生长受到抑制，而侧根原基的伸长被抑制，特别是在低硝酸盐和酸性pH值。有趣的是，Chl1突变体也显示出晚开花表型。这些结果表明，在营养生长和生殖生长过程中，CHL1被激活并在芽和根中的新生器官的生长中起作用。
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.