Root growth inhibition by NH4+ in Arabidopsis is mediated by the root tip and is linked to NH4+ efflux and GMPase activity
Root growth inhibition by NH4+ in Arabidopsis is mediated by the root tip and is linked to NH4+ efflux and GMPase activity
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DOI：
10.1111/j.1365-3040.2010.02162.x
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发表时间：
2010-09-01
影响因子：
7.3
通讯作者：
Shi, Wei-Ming
中科院分区：
文献类型：
--
作者：
Li, Qing;Li, Bao-Hai;Shi, Wei-Ming
高等植物的根系生长对过量的铵（NH 4+）敏感。我们的研究表明，NH 4+与初级根尖的接触是必需的，也是足够的，以发展的停滞根生长在NH 4+营养下的拟南芥。我们表明，细胞伸长，而不是细胞分裂是主要目标在NH 4+抑制主根生长。使用DR 5：GUS的突变体和表达分析显示，生长抑制还独立于生长素和乙烯信号传导。采用扫描离子选择性电极技术测定了NH 4+沿主根的沿着通量，结果表明，NH 4+浓度升高对根伸长有抑制作用，但对伸长区的NH 4+流出有明显的刺激作用。在缺乏GDP-甘露糖焦磷酸化酶（GMPase）的NH 4+超敏突变体vtc 1 -1中，NH 4+外流的刺激和细胞扩张的抑制显着更加明显。我们的结论是，限制跨膜NH 4+通量和正常运作的GMP酶在根中是至关重要的，以尽量减少严重程度的NH 4+的毒性反应在拟南芥。
Root growth in higher plants is sensitive to excess ammonium (NH4+). Our study shows that contact of NH4+ with the primary root tip is both necessary and sufficient to the development of arrested root growth under NH4+ nutrition in Arabidopsis. We show that cell elongation and not cell division is the principal target in the NH4+ inhibition of primary root growth. Mutant and expression analyses using DR5:GUS revealed that the growth inhibition is furthermore independent of auxin and ethylene signalling. NH4+ fluxes along the primary root, measured using the Scanning Ion-selective Electrode Technique, revealed a significant stimulation of NH4+ efflux at the elongation zone following treatment with elevated NH4+, coincident with the inhibition of root elongation. Stimulation of NH4+ efflux and inhibition of cell expansion were significantly more pronounced in the NH4+-hypersensitive mutant vtc1-1, deficient in the enzyme GDP-mannose pyrophosphorylase (GMPase). We conclude that both restricted transmembrane NH4+ fluxes and proper functioning of GMPase in roots are critical to minimizing the severity of the NH4+ toxicity response in Arabidopsis.