Babourina Olga, Newman Ian, Shabala Sergey
School of Mathematics and Physics, and School of Agricultural Science, University of Tasmania, GPO Box 252-21, Hobart, Tasmania 7001, Australia.
Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):2433-8. doi: 10.1073/pnas.042294599.
Ion flux kinetics associated with blue light (BL) treatment of two wild types (WTs) and the phot1, phot2 and phot1/phot2 mutants of Arabidopsis were studied by using the MIFE noninvasive ion-selective microelectrode technique. BL induced significant changes in activity of H(+) and Ca(2+) transporters within the first 10 min of BL onset, peaking between 3 and 5 min. In all WT plants and in phot2 mutants, BL induced immediate Ca(2+) influx. In phot1 and phot1/phot2 mutants, net Ca(2+) flux remained steady. It is suggested that PHOT1 regulates Ca(2+) uptake into the cytoplasm from the apoplast. Changes in ion fluxes were measured from cotyledons of intact seedlings and from the cut top of the hypocotyl of decapitated seedlings. Thus the photoreceptors mediating BL-induced Ca(2+) and H(+) fluxes are present in the rest of the decapitated seedling and probably in the cotyledons as well. The H(+) and Ca(2+) flux responses to BL appear not to be linked because, (i) when changes were observed for both ions, Ca(2+) flux changed almost immediately, whereas H(+) flux lagged by about 1.5 min; (ii) in the Wassilewskija ecotype, changes in H(+) fluxes were small. Finally, wave-like changes in Ca(2+) and H(+) concentrations were observed along the cotyledon-hook axis regardless of its orientation to the light.
利用MIFE非侵入性离子选择性微电极技术，研究了蓝光（BL）处理拟南芥两个野生型（WT）以及phot1、phot2和phot1/phot2突变体时的离子通量动力学。蓝光照射开始后的前10分钟内，蓝光诱导H(+)和Ca(2+)转运体活性发生显著变化，在3至5分钟达到峰值。在所有野生型植株和phot2突变体中，蓝光诱导立即出现Ca(2+)内流。在phot1和phot1/phot2突变体中，净Ca(2+)通量保持稳定。这表明PHOT1调节质外体中Ca(2+)向细胞质的摄取。离子通量的变化是从完整幼苗的子叶以及去顶幼苗下胚轴的切口顶端测量的。因此，介导蓝光诱导的Ca(2+)和H(+)通量的光受体存在于去顶幼苗的其余部分，可能也存在于子叶中。蓝光对H(+)和Ca(2+)通量的响应似乎没有关联，因为：（i）当观察到两种离子都发生变化时，Ca(2+)通量几乎立即发生变化，而H(+)通量滞后约1.5分钟；（ii）在Wassilewskija生态型中，H(+)通量变化很小。最后，无论子叶钩轴与光的方向如何，沿着子叶钩轴都观察到Ca(2+)和H(+)浓度的波状变化。
