Conflux + I&E Flux + I&M Flux = 细胞内外离子/分子同时检测完整方案

根部的离子吸收是维持植物细胞营养平衡最重要的一步，成熟区的营养吸收受茎和根尖的系统控制。这个过程受到电信号、压力、机械刺激、光照和细胞分裂素的调节。

2009年，科学家通过非损伤微测技术研究了玉米和大麦根部的离子流，发现短期的光照使H+外流减小，K+从吸收转变为外流。切断的玉米和大麦的根在低盐环境下H+外流减小，K+内流停止。加入100mM NaCl，压力剧烈变化，但是离子流不受影响。切除了大麦根尖部分，离子流从小内流转变为大的内流。激动素（2-4 μM，一种细胞分裂素）引起了K+更大的内流，说明离子的运输被根尖合成的细胞分裂素所调控。

本研究说明快速的电信号和细胞分裂素能够调节根的营养吸收，下一步的研究将集中在通过增加光强而引发的电信号如何调节植物离子运输和营养吸收。这项工作为我们如何调节植物的营养吸收提供了依据。

关键词：激动素(kinetin); 长距离信号(long-distance signalling); K+ ; H+

参考文献：Shabala S,et al. Plant, Cell and Environment (2009) 32, 194–207

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Abstract：

Nutrient acquisition in the mature root zone is under systemic control by the shoot and the root tip. In maize, exposure of the shoot to light induces short-term (within1–2 min) effects on net K+ and H+ transport at the root surface. H+ efflux decreased (from -18 to -12 nmol m-2 s-1) and K+ uptake (~2 nmol m-2 s-1) reverted to efflux (~-3 nmol m-2 s-1). Xylem probing revealed that the transroot (electrical) potential drop between xylem vessels and an external electrode responded within seconds to a stepwise increase in light intensity; xylem pressure started to decrease after a ~3 min delay, favouring electrical as opposed to hydraulic signalling. Cutting of maize and barley roots at the base reduced H+ efflux and stopped K+ influx in low-salt medium; xylem pressure rapidly increased to atmospheric levels.With 100 mM NaCl added to the bath, the pressure jump upon cutting was more dramatic, but fluxes remained unaffected, providing further evidence against hydraulic regulation of ion uptake. Following excision of the apical part of barley roots, influx changed to large efflux (-50 nmol m-2 s-1). Kinetin (2–4 μM), a synthetic cytokinin, reversed this effect. Regulation of ion transport by root-tip-synthesized cytokinins is discussed.