植物根系对氮胁迫的形态学响应

The morphological responses of the root system to the nitrogen stress

NO3-不仅是植物营养的主要N源,而且也是调节植物新陈代谢和生长发育的信号。植物根系对N供给的形态学适应表现在4个方面:(1)植物侧根(LR)响应体外硝酸盐的局部刺激而伸长,AtNRT1.1在侧根响应体外硝酸盐的局部刺激中,作用于ANR1 MADS box基因上游;(2)植物LR分裂组织活动受到组织中高浓度的硝酸盐抑制,RNA结合蛋白FCA是高硝酸盐/ABA诱导侧根发育抑制的信号传输途径成分;(3)植物侧根的发生受到体外高C∶N比抑制,AtNRT2.1参与高C∶N比抑制侧根发生;(4)植物根响应体外L-谷氨酸盐的刺激而分枝,初生根的生长受到体外L-谷氨酸盐抑制,植物根系对L-谷氨酸盐的响应可能与一种同源于哺乳动物离子型谷氨酸盐受体的植物蛋白的感知作用有关。植物根形态对N供给的响应具有重要生理和生态意义。

Nitrogen（N）,one of the most important nutrients for plants,is an important signal regulating plant growth and development.Four main morphological adaptations of the root system in response to the N supply have been reviewed：（1） A localized stimulatory effect of external nitrate on lateral root elongation.The AtNRT1.1（CHL1） dual-affinity nitrate transporter acts upstream of the ANR1 MADS box gene to mediate this stimulatory effect.（2） A systemic inhibitory effect of high tissue nitrate concentrations on the activation of lateral root meristems.The RNA-binding protein,FCA,could be a component of a signaling transduction pathway involved in the high nitrate/ABA induced inhibition.（3） A suppression of lateral root initiation by high C∶N ratios.The AtNRT2.1 high-affinity nitrate transporter seems to be involved in this repression.（4） An inhibition of primary root growth and a stimulation of root branching by external L-glutamate.This morphological response of the root system probably involves sensing by plant homologues of mammalian ionotropic glutamate receptors（iGluRs）.The root morphological responses to the N supply have important physiological and ecological significance.